car sputters

[veedubclub91]

I have a 92 vw GTI that is sputtering when accelerating, going up a hill or just when on gas at RPMs lower than 3 sometimes. I live in the mountains so I am driving up a long steep incline quiet often. It has always struggled to get up over the mountain passes but now it has gotten really bad. I can not go over 25-30 while going up. I have replaced the spark plugs, fuel filter, distributor cap and rotor. I would like to have the car running well again before cold weather sets in so any help is greatly appreciated.

[Jetta A2 1989]

Check the AFM with a ohm meter. (Bentley manual) and check afm flapper isn't sticking.
Look for walnuts and peanuts and a half eaten air filter.
Unplug the O2 sensor and see if it runs better.
Check blue coolant sensor with ohm meter. (Bentley manual)
Check for Vacuum leaks. small hoses air intake boot.
Pull every sensor plug off one at a time and check the wiring.
Injector plug, AFM, idle switch plug etc etc.......
Check/clean all grds on battery and engine.
Check engine ignition timing and timming belt.
Volume test both pumps.
That's a start.

[veedubclub91]

So I am apparently running on 3 cylinders. I disconnected one of my spark plug wire and there is no difference in power. I appear to have spark because the spark plug wire zaps me if I hold it. I havent visually seen spark though. I have checked to fuel pressure and tested the resistance of the fuel rail. The fuel pressure was right below 40 while running and dropped to about 30 after letting it sit for 10 mins. The resistance of the fuel rail was 4.9. I am taking out the injectors now to check for proper spray.

[ziddey]

Yow. Either you're downplaying getting zapped or it's weak spark. Or you were holding the non-metal part and still got zapped?

I'm assuming the other 3 have an effect when you pull the wires?

How's your cap and rotor? Try switching the offending cylinder's wire with another and see if the problem moves. How's the spark plug look?

Try resetting the ECU and running without the O2 sensor hooked up:

unplug the o2 sensor and secure wire somewhere safe
warm up the engine
with the engine running, unplug the cts. rev engine to 3k 4 times. plug cts back in.

ecu should now be reset. how does it drive now without the o2 sensor plugged in?



Check for vacuum leaks. It sounds like you have have quite a big one. Of course, if you're saying you have an issue with one cylinder, figure that out as well.

[veedubclub91]

I was holding a plyers with rubber grib holding the rubber part and still getting zapped. Yes the other 3 have a noticeable difference when I unplug them. The cap is less than 6 months old as is the rotor. Spark plugs all look pretty evenly worn and not bad at all. Those have also been replaced in the last 6 months. They are bosch platnium 4. I have sprayed all the air lines with carb cleaner to check for any leaks. The idle stayed the same. I did a compression test and all cylinders were either 150 or 155. I only have a crappy haynes manual. The AFM? Is that also the MAF? I will try and reset the ECU tom. You said to unplug the cts. What is the cts?

[ziddey]

Yes, the Air Flow Meter. These cars do not have Mass Air Flow sensors.

CTS = Coolant temperature sensor. It's the blue guy on the coolant flange coming off the middle of the head.

Do swap the wires around and see if the misfire moves.

Plat+4's suck. Good old bosch coppers are best

[tmerritt]

i'm currently having the same problem. it ran fine a week ago. i replaced the clutch then when i got everything put back together i have said problem. when i accelerate no matter what gear i'm in i lose power when i get to about 2500 rpm.

[veedubclub91]

So I was wrong about it running on 3 cylinders. I had just briefly checked if there was a difference and hadnt noticed it. It acts the same for each one of the cylinders. Is it possible that the car is just old and I am at a very high altitude. I do not seem to have any problem when I travel down. It is just when I am traveling up the passes or traveling up an incline. I was driving it today at 6000ft and it was running like a champ. I then drove back up to 8500ft where it started to sputter a little. I live at 8500ft and travel up over mtn passes that go up to 11,000ft and that is when I notice it the most. It sputters and backfires as Im going up. I am still doing testing on it but I just wondered if someone had any experience at very high altitudes.

[veedubclub91]

So while testing the AFM for resistance it failed the temp sensor check. The first couple time I check it showed 17** during a the day and the temp is somewhere in the 50s or 60s. Then a couple minutes later I tested it again and it flashed 16** for a second then showed a 1 which it shows when not connected to anything. I will be replacing the AFM and will post the results.

[veedubclub91]

ziddey-You said to unplug the oxygen sensor then unplug the cts rev it 4 times to 3k. I did that and the car runs the same. Is the oxygen sensor bad then?

I have retested the AFM temp sensor and everytime I test it, it gives no continuity. I will be replacing that. I shall keep yous informed on wether changing the AFM changes anything.

[veedubclub91]

I hear what sound like a clunking almost that sounds like it is coming from either the motor or the distributor area while idling. Could this be caused by the AFM being out of wack? I also noticed that it seem to run the worst when warmed up. I am trying to give as much detail as I can of the problem.

I am wondering if possible the timing could have somehow got out of wack. Im not sure how timing would get out of wack without the belt skipping a tooth somehow and I dont see how that could even happen. Is it possible for the timing to all the sudden just be a little off? If it is timing will this page http://forums.vwvortex.com/showthrea...t=timing+light actually work to do the timing without a light.

Also could this just be a bad ECU? Is there a way to test the ECU? I did have a bad negative cable wire which I replaced which may have caused a bad ground at one point. I know that a bad ground can cause the ECU to fry but would it still work at all and just have issues after the bad ground fried something? Thanks for any help. I am about to drive it off a cliff soon...

Would taking this to a shop and having them see if it kick any codes do any good? Would a regular shop even have a scanner that works for my car? Is there a scanner for my car?

[Fat Rabbit]

Lots of questions.

In theory a dealer can check the ECU but (at least around here) one can buy a used ECU for much less than the dealer charges to check it.

How can the timing be out of wack? There are lost of ways. The timing belt could have skipped a tooth, the timing belt could simply be old and worn, the timing belt tensioner could be worn and a key for one of the toothed pulleys might have sheared. Sometimes those keys partially sheer allowing the timing to move off just a bit. I have seen that with the crank and intermediate shaft pulleys mostly and I found one engine that had been put together without a key when it was rebuilt. If you don't know when the timing belt and idler were last changed you should change them and reset the timing. If you change the timing belt, follow the manual and use a timing light. You should be able to borrow or rent a timing light locally.

Usually a clunking sound coming from an engine is not a good thing. See if you can isolate the sound by carefully using a long screwdriver held on various parts of the engine with the handle placed against your ear. Since the engine will be running -- stay away from moving parts. FR

[veedubclub91]

I was able to check the timing after a day of fighting with the timing belt cover and all the marks line up. I will be putting it back together tommorrow. The AFM tested out the same as the one I already had. I retested them both using a higher setting and they both gave a reading then. I will continue testing things tommorrow after putting it back together. The ignition coil failed one of its test so I guess I will be ordering a new ignition coil and see if that fixes anything. I just need to know if when I am ordering a new one whether I need to get another green label coil or if any coil that is for a 92 will work.

[ziddey]

should be fine as long as it's the older cylindrical type (no California Digifant 1 coils)

[veedubclub91]

Spark plug wires fixed it