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petermegan
12-24-2010, 05:48 AM
Hi, Newby here from Australia. Just got back from a ski with my newly purchased 2000 prostar 190 LTR330. Have encountered a bad miss in the engine from idle to approx.2500rpm after which the motor comes smooth and pulls nicely to 5200rpm. The boat only has 300hours and Oil pressure,temp all fine and pulled the sparkplugs and they seem ok and even. I am suspicious of an airflow sensor or similar? Is there anyone out there with a similar experience please or suggestions as to why this may be in the low rev range and not high. Cheers

1redTA
12-24-2010, 07:50 AM
You can actually run most MAF equipped engines with out the MAF, unplug it and see if the problem goes away. I would bet the throttle position sensor is messed up, you can check it with a voltmeter. With the engine not running hook a voltmeter to the TPS. turn the throttle slowly and watch the voltage on the volt meter. It should rise smoothly to around 5 volt at WOT if the voltage shows dips or doesn't move smoothly it is bad

Engine Nut
12-24-2010, 09:08 AM
Hi, Newby here from Australia. Just got back from a ski with my newly purchased 2000 prostar 190 LTR330. Have encountered a bad miss in the engine from idle to approx.2500rpm after which the motor comes smooth and pulls nicely to 5200rpm. The boat only has 300hours and Oil pressure,temp all fine and pulled the sparkplugs and they seem ok and even. I am suspicious of an airflow sensor or similar? Is there anyone out there with a similar experience please or suggestions as to why this may be in the low rev range and not high. Cheers

The LTR does not have a Mass Air Flow sensor... you won't find a MAF sensor on any of our engines. I would take a look at the Throtttle Position Sensor though. I have included a copy of some diagnostic info that might help. I have also attached a Service Advisory regarding an issue with some of the oil pump drive gears used on LTR engines that you might want to check out. The oil pump wouldn't have anything to do with your ""Miss" problem but it is something that should be checked anyawy.

JimN
12-24-2010, 09:10 AM
Hi, Newby here from Australia. Just got back from a ski with my newly purchased 2000 prostar 190 LTR330. Have encountered a bad miss in the engine from idle to approx.2500rpm after which the motor comes smooth and pulls nicely to 5200rpm. The boat only has 300hours and Oil pressure,temp all fine and pulled the sparkplugs and they seem ok and even. I am suspicious of an airflow sensor or similar? Is there anyone out there with a similar experience please or suggestions as to why this may be in the low rev range and not high. Cheers

There's no MAF sensor- this has a MAP sensor and it's the smaller version.

The TPS can be checked with a voltmeter but if it's a very small range where the glitch occurs, it will ge there and gone before the meter has a chance to react. However, it will often register with the ECM. You can check the codes yourself using a paper clip, bent in half so the ends are equal length. Insert the ends into terminals A and B of the ALDL (it's at the rear of the motor, near the ECM, and has a black/gray connector with a plastic cap on it). Turn the key to ON and watch the check engine light flash. It will start by flashing once, then twice (this designates 12)- it will do this three times before any codes are displayed and once the codes are shown, it will flash 12 again, three times. It it doesn't show anything but 12, it doesn't have any codes stored but it could still have a problem that won't cause the ECM to display anything.

21 or 22 means it has a TPS issue
33 or 34 means it has a MAP sensor issue

If you have access to a timing light, connect it to the #1 spark plug and watch the timing light as the RPM goes through the range where the miss occurs. This needs to be done under load, meaning on the water and at speed, not the trailer. The best way to do this is by removing the motor box cover and havine one person drive and another watching the timing mark. If you see the mark jump wildly instead of advancing smoothly through the range (the timing advance should start with 10BTDC at idle and it should add 30 of advance at WOT, for a total of 40). If you see much less than 40 of advance at WOT, it could be that the knock sensor is defective or you have knock- you should hear the knock. If you hear anything that occasionally sounds like a hammer hitting the motor, shut it down and idle into the dock. If it's just pinging/rattling with hard acceleration, it could be that the compression is low or the fuel is bad. You should be using 89 octane and if the gas is old, it will be less than that.

It's possible that the ignition control (IC) module has a problem or a bad ground. Look at all of the ground points and make sure the wires attached there are clean and tight.

Jerseydave
12-24-2010, 01:05 PM
Could also be a bad coil pack. Do a power balance test and see if the engine rpm drops when you pull each plug wire one at a time. No drop in rpm means that's the problem cylinder. You can also look for carbon tracking at each coil post.

I only say look at coil pack problems because my friend had a bad one on his '01 LTR engine.

petermegan
12-24-2010, 07:36 PM
Give me a few days to try some stuff and hopefully get back with some good news, will check that oil pump drive cog too. I had read it could be a problem. Thanks guys excellent help.

petermegan
01-01-2011, 07:34 AM
Well I checked my oil pump drive cog and it must have already been replaced. It's steel and looks good. I used the paper clip method to check engine codes and there was nothing stored on the computer. I checked resistence on plug leads all good. In desperation I have sprayed some carby cleaner in to the IAC, replaced plugs and have fitted an aftermarket TPS and problem fixed. I am not exactly sure which one of these cured the problem, maybe a combination of all three? Thankyou very much for all your help guys, once again great responses. Cheers

JLMax16
08-03-2012, 09:23 PM
Well I checked my oil pump drive cog and it must have already been replaced. It's steel and looks good. I used the paper clip method to check engine codes and there was nothing stored on the computer. I checked resistence on plug leads all good. In desperation I have sprayed some carby cleaner in to the IAC, replaced plugs and have fitted an aftermarket TPS and problem fixed. I am not exactly sure which one of these cured the problem, maybe a combination of all three? Thankyou very much for all your help guys, once again great responses. Cheers

What did you do for the TPS?

petermegan
08-04-2012, 05:22 AM
It was a while ago now but found one on Ebay for $25. I think original had AC and possibly a part number that I cross referenced. Sorry it was too long ago to remember exactly, but they are readily available.

BG1772
08-04-2012, 08:25 AM
The TPS for an LTR330 is the same as the one used on a 1988 GMC Yukon 5.7 L. I got mine at NAPA for about $25.

I've found that the 88 Yukon is a good vehicle to use when you go to a parts store that insists that you give them a base vehicle to use as a starting point into their computer system.

JimN
08-04-2012, 09:24 AM
Well I checked my oil pump drive cog and it must have already been replaced. It's steel and looks good. I used the paper clip method to check engine codes and there was nothing stored on the computer. I checked resistence on plug leads all good. In desperation I have sprayed some carby cleaner in to the IAC, replaced plugs and have fitted an aftermarket TPS and problem fixed. I am not exactly sure which one of these cured the problem, maybe a combination of all three? Thankyou very much for all your help guys, once again great responses. Cheers

Good to see it's working.

Did any of the plug wires come off more easily than you expected? Could have had a couple that weren't seated properly.

One thing about checking plug wires- using a meter doesn't tell more than just continuity. What a Sun diagnostic machine does (if you have seen the big machines with a CRT screen in a service shop, Sun is one of the companies that makes them), is show the signal going to each plug and it's very easy to see if the current is higher, lower, absent or intermittent. It's possible to have continuity at rest and no spark at high RPM. If this problem returns and you have access to a timing light, you can place the pickup clip as close to each plug boot as possible to see if the spark is absent and then slide the pickup along the wire to see if/where it starts. If you hear a snapping sound when it's running, you would need to look for arcing between wires, the wires and the metal engine parts, or at the coil packs.

petermegan
08-04-2012, 09:36 AM
Hi Jim, That was my first post from 18mths ago, but boat still runs perfect, thankyou for your help back then. cheers.

JimN
08-04-2012, 11:29 AM
Hi Jim, That was my first post from 18mths ago, but boat still runs perfect, thankyou for your help back then. cheers.

I guess I should have looked at the date.