PDA

View Full Version : Hard Cold Start @ Low Rpm miss


KHall
11-30-2009, 09:56 PM
Have a 03 X2 with 5.7L Predator TBI.

Will not start cold unless throttle is open. Once it starts it misses badly and produces whitish smoke. Still won't idle at this point. But would take off and cruise with throttle open. I have to jam in gear to get it away from dock, to keep well above idle to allow warm up. It remains finicky for first few pulls. It does have decent if not full power. thought i had no check engine light but just noticed the lights doesn't even come on at key on anymore.

Upon warming up to 150F plus for awhile it then runs fine, idles and re starts at an idle. 100 % difference.

Have just replaced: Spark Plugs, Cap/Rotor.
Plug Wires have about 175 hrs on them.
Compression Test: I did it wrong, but OK results. 200 ave, 190 low, 210 high.

Symptoms started occurring right after a fill at a gas station i have never used before. Prior to that started and run fine, except recent fuel pump issue. Guess I still need to pull some fuel and check for water, but could i be looking problems with the IAC actuator or TPS sensor? Like to go to dealer, but really can't currently afford to.

KHall
12-01-2009, 10:18 PM
Pulled the Idle Air Control Actuator and it opens some when ign key is on and closes upon key off. Will test temperature sensor next. Then i have to fix the check engine light and try to pull some codes. To bad i didn't notice the light was dead earlier.

JLeuck64
12-01-2009, 10:51 PM
Get that gas outta there!!!

JimN
12-02-2009, 05:29 AM
Take a fuel sample, preferably after either rocking the boat vigorously or trailering it. If you see water droplets or cloudy gas, get rid of it. The TPS and IAC have nothing to do with whitish clouds when it starts and you even posted that it started immediately after filling at a different gas station. Logic wouldn't point to any of the sensors.

KHall
12-02-2009, 08:29 AM
Will do, I didn't think the motor would run fine (hot) with bad gas, but problems did start with the 5 gallon top off at a new station.

KHall
12-02-2009, 10:04 PM
Rocked the boat for 3 minutes, seemed like forever. I only trailer 5 minutes to the ramp. Only difference is more hills going to ramp which would mix things up more. Drained about 4 cups, dumped it, pulled another 2 cups. Its quite clear with no signs of water, even after sitting for 3 hrs. Still like to trailer it to the ramp and take a bigger sample, but first sample looks to be clean.

There only some whitish smoke on initial rev up, starting with the throttle open. then it just doesn't idle and misses like mad until warmer and higher than 2000 rpms.

Temperature sensor 2600 ohms at room temp. Seems reasonable. Wonder what ohms i should see on these wires back to ecm?

Wonder if the coil could be acting up when its cold?

cbryan70
12-02-2009, 10:08 PM
could be the spark plug wires......

JimN
12-02-2009, 10:35 PM
Rocked the boat for 3 minutes, seemed like forever. I only trailer 5 minutes to the ramp. Only difference is more hills going to ramp which would mix things up more. Drained about 4 cups, dumped it, pulled another 2 cups. Its quite clear with no signs of water, even after sitting for 3 hrs. Still like to trailer it to the ramp and take a bigger sample, but first sample looks to be clean.

There only some whitish smoke on initial rev up, starting with the throttle open. then it just doesn't idle and misses like mad until warmer and higher than 2000 rpms.

Temperature sensor 2600 ohms at room temp. Seems reasonable. Wonder what ohms i should see on these wires back to ecm?

Wonder if the coil could be acting up when its cold?

I posted a temperature/resistance chart here but I can't find it at the moment. If the resistance is too low, it indicates a high temperature and the stumble at 2000RPM tells me that it thinks the motor is overheating. The steam tells me the same thing- how old, and in what condition, is the impeller? Have you checked the oil cooler recently? Both or either would cause all of these symptoms.

Crack the throttle next time when you crank it cold- if it fires up, look into the ECT and it's wiring. Also, look into the exhaust from the rear- open the flappers and look for any blistering of the rubber flappers, hoses or the flanges.

KHall
12-03-2009, 12:33 AM
There is a post by engine nut with the ohm readings. I went by those numbers. Compared old sensor to new sensor at parts store and it was very close on ohms. Would like to check the wires to ecm, not sure how many ohms i should be seeing. Believe ECT is the sensor i am talking about, engine coolant temperature. There is not alot of smoke or steam on start up, it might even be a little darker than white, but it only produces the smoke for couple of rev ups, then it just misses.

It does start when cracking the throttle, that's how i have been starting it. Not sure its rpm limited, it feels like it would run more than 2000 rpm, just i don't like to take off too much until it warms up.

Not overheating can, can barely get it to operating temps. Impeller has 80 hrs on it. Oil cooler is free and clear, checked it when i just drained the block for the upcoming cold nights.

There is no blistering in the exhaust. I looked at and in the flaps. Its never been overheated. I put in a new impeller every season.

JimN
12-03-2009, 09:29 AM
There is a post by engine nut with the ohm readings. I went by those numbers. Compared old sensor to new sensor at parts store and it was very close on ohms. Would like to check the wires to ecm, not sure how many ohms i should be seeing. Believe ECT is the sensor i am talking about, engine coolant temperature. There is not alot of smoke or steam on start up, it might even be a little darker than white, but it only produces the smoke for couple of rev ups, then it just misses.

It does start when cracking the throttle, that's how i have been starting it. Not sure its rpm limited, it feels like it would run more than 2000 rpm, just i don't like to take off too much until it warms up.

Not overheating can, can barely get it to operating temps. Impeller has 80 hrs on it. Oil cooler is free and clear, checked it when i just drained the block for the upcoming cold nights.

There is no blistering in the exhaust. I looked at and in the flaps. Its never been overheated. I put in a new impeller every season.

What is the air and water temperature? If both are low, the white water vapor are normal. If the air and water temperature are close to 70 and it's dense white, make sure the hub of the impeller hasn't let go. I think it's time to hook it up to run diagnostics.

If you check the wires from the ECT to the ECM, you can set the meter to Ohms and just do a continuity test. You can leave the harness plugged into the ECM for this but you'll need to leave the key OFF, remove the ECT, use a jumper and do a reference test of the test leads.

Witness140
12-03-2009, 09:41 AM
I just went through something similar with the TBI 350 chevy in my 87' K5 plow truck. It was the coolant temp sensor.

I haven't looked at my MCX, and haven't seen a Predator to see if it has a coolant temp sensor, so take this info fwiw only.

I can tell you that a bad coolant temp sensor will throw a "service engine soon' light and a code, at least it did in my truck with OBD-I. Much simpler to read the code in the truck, with the paperclip trick. I'm sure it would be much more complicated with my MCX.

Anyways, the coolant temp sensor was $15 at autozone, and took me all of 5 minutes to replace. Truck ran fine after that, so if the Predator has one, just spend the $15 and replace it rather than tearing your hair out with testing it etc.

The truck, btw, would crank and start when cold. As soon as it hit operating temp, it would quickly load up, cough, and die. Then it would crank, and only fire with full throttle. Then it would spit black soot and smoke out the exhaust and still wouldn't run. I've heard of different variations of the CTS problem, but this was mine.

My truck is TBI. Not sure if there are any similarities between that original TBI and the current version. I heard one trick a guy employed to get his truck home. He disconnected the TPS and one injector, and was able to limp it home like that. Kept it from completely flooding out and allowed it to run.

87MC owner
12-03-2009, 04:00 PM
Funny, my 87 Prostar does this as well. She starts up fine on the trailer even after sitting for a few months but once warm and in the water, it turns over slowly and somtimes even stalls without giving it gas. I have been playing with the idles but then it simply slams into gear once running.What gives?

KHall
12-03-2009, 04:58 PM
This started when the temps dropped, def below 70 air and water. The impeller is fine.

Maybe i can just get a couple of block heaters and skip the crappy warm up phase. If i could just hit the water with a 150F motor, then all would be well. :)

I wish this was my temperature sensor/wires, but now feeling a little more pessimistic.

KHall
12-03-2009, 05:44 PM
Well i continue to do things tail backwards. Prob from overly rushing, many problem issues in my life. Anyway, I went out to pull some trouble codes. I forgot to hook up the TPS, IAC, and CTS wiring plugs, just dumb. I then flashed two code 81's. Don't know if these where there or due to the three sensors not plugged in. Overall got : 12 12 81 81 12 12.

Believe the 12's are normal. Does anyone recognize Code 81?

KHall
12-03-2009, 05:58 PM
Think the 81's are injector codes one for each, maybe due to me also having throttle open. I'am clearing the codes and gonna maybe try running it this sunday. Its odd that when i changed the cap and rotor it worked perfectly the next sat morning, then on sunday Then the same missing/stalling until warmed up. Maybe I wiggled something in the distributor??

KHall
12-03-2009, 05:59 PM
Four posts in a row ... too much coffee today.

KHall
12-04-2009, 10:24 PM
What is the air and water temperature? If both are low, the white water vapor are normal. If the air and water temperature are close to 70 and it's dense white, make sure the hub of the impeller hasn't let go. I think it's time to hook it up to run diagnostics.

If you check the wires from the ECT to the ECM, you can set the meter to Ohms and just do a continuity test. You can leave the harness plugged into the ECM for this but you'll need to leave the key OFF, remove the ECT, use a jumper and do a reference test of the test leads.

Not sure if i understand the "jumper and reference test part." I connected the meter to the sensor end of the ECT circuit with the wires connected to the ECM. I did not read continuity but saw 1,500 ohms. Will a scanner do? or is it time for someone with Diacom?

JimN
12-04-2009, 10:59 PM
Not sure if i understand the "jumper and reference test part." I connected the meter to the sensor end of the ECT circuit with the wires connected to the ECM. I did not read continuity but saw 1,500 ohms. Will a scanner do? or is it time for someone with Diacom?

If you do it that way, you're trying to read through the ECM and that's not what you need to know. You need to know the resistance of the sensor and the two ways to read that are by connecting the meter to the sensor itself or by unplugging the harness from the ECM and read through the harness through the ECT. This would be more accurate (more similar to what the ECM sees) than measuring the sensor but either will work- if the sensor is far out of range, it'll be way off either way.

When I mentioned a jumper, it was to measure the resistance of the wires from the ECM to the ECT. Unplug the wires from the ECT and put the meter's test leads on the two pins to read the resistance. If it's below a few thousand Ohms, it's toast. You can also check the resistance changes by removing the ECT, measuring the resistance, putting it in hot water and watching the value change.

JimN
12-04-2009, 11:06 PM
Well i continue to do things tail backwards. Prob from overly rushing, many problem issues in my life. Anyway, I went out to pull some trouble codes. I forgot to hook up the TPS, IAC, and CTS wiring plugs, just dumb. I then flashed two code 81's. Don't know if these where there or due to the three sensors not plugged in. Overall got : 12 12 81 81 12 12.

Believe the 12's are normal. Does anyone recognize Code 81?

I'm not aware of an 81 code. EngineNut would be able to verify that. You should have seen a 21 (TPS low) and a 15 (ECT resistance low). The IAC won't throw a code at all. You didn't hurt anything by leaving the harnesses off but you need to plug them in and check it again. I know it's a pain but it needs to be done.

JimN
12-04-2009, 11:11 PM
Think the 81's are injector codes one for each, maybe due to me also having throttle open. I'am clearing the codes and gonna maybe try running it this sunday. Its odd that when i changed the cap and rotor it worked perfectly the next sat morning, then on sunday Then the same missing/stalling until warmed up. Maybe I wiggled something in the distributor??

Codes are stored only through sensors or control devices that report to the ECM. The ECM supplies a ground reference to the injectors and the positive voltage comes from a relay that latches only when the ECM sees ≥300 RPM, which signals that it's idling. Below that RPM, it's only cranking.

If you check the codes again, look for a 41 or 42 code- that would be the ignition control module (IC Module) and it can be intermittent. Make sure the screws that hold the IC Module in place aren't terribly rusted, the distributor base is in good contact with the block (the distributor grounds through the base) and the resistance from the IC Module screws to the block is low.

KHall
12-04-2009, 11:19 PM
Thanks, The ect sensor did check out ok.

JimN
12-04-2009, 11:29 PM
Thanks, The ect sensor did check out ok.

Have you checked the fuel pressure yet?

KHall
12-05-2009, 08:21 AM
First thing i did, 30 psi, always, idle and running under load.

JUST-IN-TIME
12-06-2009, 12:30 PM
you need 2 do this

fuel
low pressure reading
high pressure readings

compression check
cap and rotor check

also if your just reading codes and not using a computer, you going to be in a lot of hunting
if you have no clue how EFI works, i can send you info

the 81 is injector codes, seen this once when they had a bad ground


are you using computer?
if so log it and send me the info


oh and using OHMS is not what you want to to, test voltage first at the sensors and use their ground!!

KHall
12-06-2009, 03:32 PM
you need 2 do this

fuel
low pressure reading
high pressure readings

compression check
cap and rotor check

also if your just reading codes and not using a computer, you going to be in a lot of hunting
if you have no clue how EFI works, i can send you info

the 81 is injector codes, seen this once when they had a bad ground


are you using computer?
if so log it and send me the info


oh and using OHMS is not what you want to to, test voltage first at the sensors and use their ground!!

Fuel = 30 psi all the time, both at idle and running under load.
Compression 200 psi
Cap and Rotor are new, when replaced these it started fine next morning, then did not work the next two times out. By work i mean hard cold start and missing until fully warmed up. Also checked PVC and put in new plugs.
I do understand how EFI works, the sequence of operations are kinda simple. But not much practice with proper tools. Also have a PCM service manual for MEFI4.
Believe Code 81 can mean other things besides injectors, for example the cam position sensor and ECM reference voltage.
Been trying to talk myself into getting MEFI Scan or just going to dealer. I would use this before manually testing all of the sensor voltages.
Appreciate the offer to review the data, will do. I really have a tight budget on this, otherwise i'd just go to dealer.

JimN
12-06-2009, 08:33 PM
you need 2 do this

fuel
low pressure reading
high pressure readings

compression check
cap and rotor check

also if your just reading codes and not using a computer, you going to be in a lot of hunting
if you have no clue how EFI works, i can send you info

the 81 is injector codes, seen this once when they had a bad ground


are you using computer?
if so log it and send me the info


oh and using OHMS is not what you want to to, test voltage first at the sensors and use their ground!!

This is OBD I and the injectors don't throw codes. Cars of that year were a lot farther ahead in terms of technology than marine applications.

Ohms will reveal bad terminals, wires and bad ECT. I do agree that the voltage should be checked at the sensor, though.

JUST-IN-TIME
12-06-2009, 11:01 PM
This is OBD I and the injectors don't throw codes. Cars of that year were a lot farther ahead in terms of technology than marine applications.

Ohms will reveal bad terminals, wires and bad ECT. I do agree that the voltage should be checked at the sensor, though.



yes they do!!!!

this is MEFI not OBD, this is a boat man not a car

03 motor, hahahah
cars where getting passed in EFI tech then!!!

cars are now trying to keep up with airplanes and boats, hence digital throttle and shift

im not arguing here at all, just trying to help people out that do not know






what computer u using?

diacom? or CDS, or CDX?

only 3 programs out there unless u have the 2K programmable sheet

JimN
12-07-2009, 12:01 AM
yes they do!!!!

this is MEFI not OBD, this is a boat man not a car

03 motor, hahahah
cars where getting passed in EFI tech then!!!

cars are now trying to keep up with airplanes and boats, hence digital throttle and shift

im not arguing here at all, just trying to help people out that do not know


what computer u using?

diacom? or CDS, or CDX?

only 3 programs out there unless u have the 2K programmable sheet

Unless Indmar and MC had a meteoric rise in technology with the TBI motor between '01 and '03, the injectors do not cause a code. I was an MC tech until March of '01 and the last time I was at MC training in October of 2000, the throttle body motors didn't do much more than my '90 Chevy pickup other than have a better intake manifold, roller cam/rockers and Vortec heads. The newer generation motors with coil near plug may have this but the TBI surely does not.

FYI- Corvette has had throttle by wire since about '94- boats are not up to the same level as cars, not do they need to be. OBD refers to OnBoard Diagnostics and the boat that's the topic of this thread has throttle body, not multi-port injection.

JUST-IN-TIME
12-07-2009, 01:16 AM
they had a major jump after 02, when carb 3 went to effect, i bet the mentioned it in training about newer regs

cool you were a tech!!!

you want the mefi book? volvo, merc, indy, PCM?
i have them all, good info all the same sheet ya know, you need 5v and a ground

you should read up

the marine industry just caught up to airlines in 03, we surpassed them on 08 with cats!!!!

JimN
12-07-2009, 09:21 AM
they had a major jump after 02, when carb 3 went to effect, i bet the mentioned it in training about newer regs

cool you were a tech!!!

you want the mefi book? volvo, merc, indy, PCM?
i have them all, good info all the same sheet ya know, you need 5v and a ground

you should read up

the marine industry just caught up to airlines in 03, we surpassed them on 08 with cats!!!!

When I was there last time, one of the dynos had a motor with an 02 sensor on it, which had been in development for a couple of years already and we had discussed since '99. We had also discussed how MC would be doing TBW and the catalytic converters and how CARB/Congress don't have a clue about what it takes to put emissions control on something with wet exhaust.

I have all of the MC/Indmar manuals from '97-'02 and I don't work on boats much anymore, thanks.

KHall
12-10-2009, 05:48 PM
Hooked it up the Laptop with a basic scanning tool. In a hurry as usual, but managed to see;

Key On engine Off:

ECT sensor about right temp.
TPS .57 closed and well over 4.0 wide open
Map sensor voltage over 4.6 i think.
IAC valve at 111 counts.
Inj A and Inj B were 32.2 ms

Hope to run it this weekend, I'am predicting there's a great chance i'll end up siphoning the gas out of the tank. What to do with 25+ gallons?

CruisinGA
12-10-2009, 06:12 PM
If it was me, I would dump it in my '74 Land Cruiser or '53 Willys and burn it. Do not put it in power equipment.

KHall
12-10-2009, 06:15 PM
If it was me, I would dump it in my '74 Land Cruiser or '53 Willys and burn it. Do not put it in power equipment.

Earlier I was staring at the lawnmowers. Why not power equip?

JimN
12-10-2009, 09:24 PM
Hooked it up the Laptop with a basic scanning tool. In a hurry as usual, but managed to see;

Key On engine Off:

ECT sensor about right temp.
TPS .57 closed and well over 4.0 wide open
Map sensor voltage over 4.6 i think.
IAC valve at 111 counts.
Inj A and Inj B were 32.2 ms

Hope to run it this weekend, I'am predicting there's a great chance i'll end up siphoning the gas out of the tank. What to do with 25+ gallons?

IIRC, you removed the IAC so I would see if you can repark it with the program you have. The IAC doesn't report to the ECM, the ECM assumes it's closed during repark and if the pintle moves without the ECM being energized, the ECM can think it's in one place when it's in another. That can easily cause a problem with how it runs- if it's open too far, it runs lean.

CruisinGA
12-10-2009, 10:44 PM
Small tubes and carbs, easy to clog, corrode etc.

4 stroke lawnmower would probably be fine, but I would definitely not mix it with 2 stroke oil.

If ethanol in fuel can kill a 2-stroke, imagine what water etc can do. Since 2-stokes depend on the fuel for critical engine lube, want to make sure that fuel is good.

KHall
12-12-2009, 02:34 PM
Boat runs like a champ with no trouble codes. Did three things in the last round:

Cleaned up ground of IC module
Replaced IAC Valve, i had dropped original on the concrete floor.
Disconnected battery overnight to charge it.
24 F overnight, 32 degrees out it fired right up and idled with throttle closed.:)

At idle the IAC counts varies, 1 to 5 counts, it goes up to 15 counts when placed in gear.

1redTA
12-12-2009, 04:51 PM
FYI- Corvette has had throttle by wire since about '94- boats are not up to the same level as cars, not do they need to be. OBD refers to OnBoard Diagnostics and the boat that's the topic of this thread has throttle body, not multi-port injection.[/QUOTE]

I thought the vette went to drive by wire in 97 when it was powered by the ls1?

JimN
12-12-2009, 07:11 PM
FYI- Corvette has had throttle by wire since about '94- boats are not up to the same level as cars, not do they need to be. OBD refers to OnBoard Diagnostics and the boat that's the topic of this thread has throttle body, not multi-port injection.

I thought the vette went to drive by wire in 97 when it was powered by the ls1?[/QUOTE]

If the boat is open loop, it's OBD-I. They could have OBD-i with closed loop but with all of the rest of what OBD II can do, it would be overkill but even multi-port has been used with OBD-I, like the LT-1 and LTR. AFAIK, they won't need to use OBD-II unless CARB and the EPA go totally nuts. They just don't understand why boats can't/shouldn't be run as lean as cars and I doubt they ever will.

I could be wrong about when GM started using TBW on production cars- could be that my friend talked about it when they were still developing it, since he worked in V8 Powertrain Development.