3000 RPM Hesitation
08-21-2002, 12:36 PM
#1
Junior Member
Thread Starter
Join Date: Aug 2002
Posts: 14
The hesitation that some 3rd gens experience at, or, around 3000 rpm is a pain. It is a relatively common problem, probably related to at least one design glitch. I have read about various fixes people have tried with mixed success (kind of like an alergy or genetic disorder), however, most of that information is a little old. My car developed the stutter around 24,000 miles and I have tried many of the fixes that I have read about.... improving grounds, changing ignition wires, plugs etc. but nothing has worked. I have not gone to the extreme of replacing the ECU. Does anyone have any new ideas on for to get around this problem??
08-21-2002, 01:22 PM
#3
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
the hesitation is caused by current spikes in the engine ground circuit (just like the 86-88's). the ecu is grounded to the top of the engine and then the engine is grounded to the body then battery. the fix which should get rid of about 90% of it, is the following.
1. there is a wire between the rear of the upper intake and the body.
remove it, clean and put dielectric (sp?) grease on the contact. take the tab off the body of the car. clean its mating to the car, and also grease. make sure the wire clips in tight. tighten all the bolts
2. the negative battery cable bolts to the engine block under the ac bracket. clean grease and tighten.
3. the relay box next to the shock tower is on a big metal bracket. clean and tighten the bracket to car surface.
4. clean and tighten the battery cable ends
#1 and #3 are the most critical i was able to fix 85% of mine just with those 2, they are also the easiest to reach.
the reason for the grease is to keep the surfaces from corroding, i didn't grease mine, and had to do it again a year later.
the next step in the diagnistic chain is to replace the ecu, and after that the engine wiring harness
mike
1. there is a wire between the rear of the upper intake and the body.
remove it, clean and put dielectric (sp?) grease on the contact. take the tab off the body of the car. clean its mating to the car, and also grease. make sure the wire clips in tight. tighten all the bolts
2. the negative battery cable bolts to the engine block under the ac bracket. clean grease and tighten.
3. the relay box next to the shock tower is on a big metal bracket. clean and tighten the bracket to car surface.
4. clean and tighten the battery cable ends
#1 and #3 are the most critical i was able to fix 85% of mine just with those 2, they are also the easiest to reach.
the reason for the grease is to keep the surfaces from corroding, i didn't grease mine, and had to do it again a year later.
the next step in the diagnistic chain is to replace the ecu, and after that the engine wiring harness
mike
09-01-2002, 05:49 PM
#4
Junior Member
Thread Starter
Join Date: Aug 2002
Posts: 14
OK, so I first tried cleaning up the connections on the ground cable that runs from the extension manifold to the fire wall but the problem remained. Before going on to the fuse box, I bought a length of 8 gauge copper wire, fitted it with spades and bolted one end to a vacant hole at the back of the extension manifold and the other end to the fire wall where the existing braided engine ground attaches. Presto, no more hesitation!
09-01-2002, 10:30 PM
#5
Senior Member
Join Date: Jun 2002
Location: La Plata, Maryland
Posts: 9,725
I'd be surprised if it doesn't come back. I did your fix about a year ago. I corrected it for a month or so then it came back.
It doesn't bother me much any more to be honest with you. It's part of the cars personality and I have just accepted it. Until I gp w/ a Power FC of coarse.
It doesn't bother me much any more to be honest with you. It's part of the cars personality and I have just accepted it. Until I gp w/ a Power FC of coarse.
09-02-2002, 05:53 AM
#6
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Thread Starter
Join Date: Aug 2002
Posts: 14
Clearly the hesitation is due to in sufficient grounding (at least in my case). If it comes back then it suggests to me that another ground is faulty and needs work. Obviously, finding the bad connection becomes problematic. How would replacing the ECU help when the bad connection, or connections, still exist?
09-02-2002, 08:07 AM
#7
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Join Date: Jun 2002
Location: La Plata, Maryland
Posts: 9,725
Well everyone I know that has went with the PFC no longer has the problem.
When did you determine it to be a grounding problem?
I think that is part of the problem but certainly not it. Think Injectors.
When did you determine it to be a grounding problem?
I think that is part of the problem but certainly not it. Think Injectors.
09-03-2002, 01:05 PM
#8
Senior Member
Join Date: Sep 2002
Location: Alexandria Va
Posts: 657
Well if it does come back try this:
Dissconnect the O2 sensor from the back of the UIM. This does it just fine for all of my big hesitations every time. I discovered this when driving around one day with Rays Wideband. The car never stuttered one time. Took it out and plugged her back up and bam stuttering like a big dog. So give it a shot.
-Rikki
Dissconnect the O2 sensor from the back of the UIM. This does it just fine for all of my big hesitations every time. I discovered this when driving around one day with Rays Wideband. The car never stuttered one time. Took it out and plugged her back up and bam stuttering like a big dog. So give it a shot.
-Rikki
09-03-2002, 01:53 PM
#9
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Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by Silver Bullett' date='Sep 2 2002, 03:53 AM
Clearly the hesitation is due to in sufficient grounding (at least in my case). If it comes back then it suggests to me that another ground is faulty and needs work. Obviously, finding the bad connection becomes problematic. How would replacing the ECU help when the bad connection, or connections, still exist?
mike