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Low RPM stutter

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C

cuda6pak

Member
Joined
Oct 10, 2004
Messages
468
First off I'd like to say I'm now an official member of TurboBuick as I just picked up my 87 GN this weekend :cool:

Quick list of pertinant mods - girdled motor with je forged pistons, ported stock irons, terry houston downpipe with hooker exhaust, PTE44 @ 16psi 93 octane, TurboTweak chip, art carr tranny with art carr 3000 n/l conv. Has new coil pack, plugs, and wires.

As for the problem, when accelerating from a stop it seems to stutter around and not know what to do until I get going through the RPMs and moving on up. It doesn't do it all the time however, sometimes it's worse sometimes its not bad. It doesn't sound like it's missing though, just stuttering. For example on the interstate it is pretty smooth. It only does this while accelerating from low rpm, whether WOT or part throttle. But once it gets up to 3000+ or so it clears out and runs great up top through all the gears. Even if I try to brake boost from a stop it's stuttering around and can't hold a steady boost or rpm.

The first thing we thought of was the MAF. The car has a new remanufactured autozone special MAF for an 87 GN. Now that tipped me off first as the problem since they seem to be junk from what I've read. However I went ahead and cleaned it with electrical contact cleaner to be safe, as well as the IAT sensor. However there was no change in driveability. Should I go ahead and pick up an LT1/LS1 with a translator to rule this out?

And no I don't have a scantool device just yet, planning to pick up a Scanmaster real soon. I was just hoping you guys could give me advice on where to look until I can scan around and see what everythings doing. I also read somewhere on here some people were having luck with cleaning the tar off the "cooling fan relay" wires or something? Where are those at?
 
Start car while running disconect MAF connector does it run any different? If ya just want to go lt1 or ls1 its not a bad idea its what i did due to Mafs for these cars bein hit or miss.
 
Are you talking just idle qualities or actually driving around? Because even free revving it it acts fine.
 
Reminds me of the time I found the coil/module bracket nuts weren't tight. Be sure the nuts under the module are tight too.
 
There are several areas that could be effecting your driveability. I might venture to say it could be the fuel filter.

Have you taken the car through the spring clean tune up routine? I might suggest looking at the plugs, plug wires and as mentioned earlier fuel filter. These are all areas that might produce the studder you speak of.

But I do tend to agree with the others. It seems like fuel issue, which leads us to the MAF. Anybody with a known working MAF near you?

I do have a question, is the IAT plugged in, oh I see you cleaned it so it must be.
 
Mad_Trbo said:
There are several areas that could be effecting your driveability. I might venture to say it could be the fuel filter.

Have you taken the car through the spring clean tune up routine? I might suggest looking at the plugs, plug wires and as mentioned earlier fuel filter. These are all areas that might produce the studder you speak of.

But I do tend to agree with the others. It seems like fuel issue, which leads us to the MAF. Anybody with a known working MAF near you?

I do have a question, is the IAT plugged in, oh I see you cleaned it so it must be.
Click to expand...

I will check the fuel filter when I get a chance. I know my 95 Cobra that I had had a stutter caused partially by the fuel filter, although it was only up top when I got on the gas that it would do that, idle and part throttle were unaffected, which would make sense. I'm still waiting on an LT1 MAF and translator from a fellow board member. There is no one really near me that I could swap and check with...
 
Maybe I missed it, but I don't see where anyone answered your question about the cooling fan relays & the black tar. They're on the drivers side inner fender well. There should be 3 of them, the big one is for running the fan after shut down in extreme heat cases. A lot of people unplug that to avoid a dead battery situation down the road. The other two I believe are the high & low speed fan relays. My car's performance improved after I cleaned all the tar out of those two connectors.

The little white tab in the plug comes out once you release it from underneath inside the plug. The pins or connectors are released by using a tiny flat head screwdriver going in from the face of the plug, each slot has a tiny lock notch in it, followed by some tugging at the wires. Be sure to write down the order in which they came out. I also disconnected the battery before doing this.

I used laquer thinner in a jar with a lid for the plastic plug itself, shake'n'bake style. I used a rag with laquer thinner & a screw driver for the connectors & the relay pins, careful of the fender paint!

I also added a tiny dab of conductive grease to each connector once done.

PS: You might take the cap off the cam sensor & check that the ring inside is still secure & not wobbling about.

Good luck!
Jimmy
 
I put on the 3.5" LT1 MAF and translator I got from a fellow member here and the car is running much better all around, just a hint of stutter right off idle but sometimes you can't even notice that. Idles better, drives better, WOT is better. Just thought I'd let everyone know what fixed it! :cool:
 
The off idle stutter could be what's known as "tip In" stumble. Some have cleared it up by fuel adjustments and/or different chips. I believe most with 009 injectors experience this issue.

Dannyo
 
Has your car been sitting very much during the past year?

I bought a TTA in CA that was not driven much for more than one year. It was timid to say the least accelerating from an idle. By the time I'd done several Spring cleanaing items and driven it 1500 miles back to Colorado (After a couple bottles of Chevron Techron fuel system cleaner), it ran like a different car. These cars run better when they are driven often. HTH :)

Your TT chip should get rid of classic 'tip in' stumble. Borrow a known good MAF and switch them out. Always check the grounds on the firewall leading to the head....Bad grounds are likely, and do affect drivability.

Spring Cleaning is a good idea in any case. :)

P.S. You need a scan tool ASAP & before youi do any modifications! Don't wait.
 
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