KOHV94

Car: 1987 camaro with 305tpi and 5spd manual.
Hello. I got a problem with my car. It kinda stutters, or jerks abit when I'm cruising in any speed. I've noticed that the "Shift Up" - light sometimes blink when it happens.
The car idles well, and runs normally when I'm accelerating. It just happens when I'm just applying enough gas to keep it from slowing down.

So far I've tested the TPS, and it shows 0.542 volts. Anyone else know what could be messing things up? The Egr? Injectors? Fuel filter or pump?

Thanks.

KyleF

Do you have a way to log data? Any codes?

An intermittent issues like this is best caught with scan data. The best I can think of based off what you are describing is electrical. Check MAF connection, grounds, and possibly coil or ICM isn't enjoying vibrations any longer. I doubt it is fuel system related unless the system is being told to do something wrong. As in, I don't think your fuel pump or injectors are randomly failing just during cruising. Unless it is an issue in the wiring, in which case jiggling the harnesses around should be able to reproduce this, and I think you would still have it under acceleration.

KOHV94

I haven't checked out the codes, as I haven't seen any check engine-lights. Is there a way for me to get the codes without a reading-device? Also, can you tell me where the OBD is located? Sorry, I haven't owned this car for long.

It does accelerate well, without any problems at all. (Which is weird) It can be a little twitchy on the throttle when the engine is warm though. The stuttering happens around 1500-2000 rpms

KyleF

OBD data port is right above your right knee when you are sitting in the drivers seat. Should see a little rectangular plastic plate facing you that you can pop off.
Yes, if you have a scan tool, you can see flagged codes that are no longer keeping the CEL on. I have a Laptop with both Tuner Pro RT and WINAldl installed. A $80 cable from MOATES.NET was all that was needed. The software is free to download (but you should swag the developer a few bucks if you use it often). I can see code (mine is 36) with a check on it but no CEL on while the car is running.

You can get codes with a paperclip. I think across the AB terminal... do a search it is easy to find with a diagram.

You should also get a fuel pressure test kit. Check KOEO pressure, Idle with Vac pressure, Idle without Vac Pressure, and then a 30 minute leakdown
You should Ohm your injectors both hot and cold.

Comparison information is easily found on the boards.

Have you done the basic maintenance items like fuel filter, base timing, IAC housing clean and perform a reset?

May need to check for timing chain stretch.

Just some thoughts off the top of my head. Hopefully doing some diagnostics will help flush something out.

ironwill

The blinking 'shift up' light might provide a clue; I'd next check the Ignition Control Module, which is responsible for generating a tach signal to the ecm.

There's info on how to do this here:https://easyautodiagnostics.com/gm/4...ed-icm-tests-6

KyleF

That's good info right there.

I agree with the ICM being the possible root cause as well. Might be the place to start.

KOHV94

Thank you for good answers, I'll check those out and see if that can be the source of my problems

KyleF

Any updates?

KOHV94

Sorry guys, I haven't gotten a chance to check for faults yet. I had a wedding I had to participate in, and I recently found out that my granny is hospital and is most likely going to pass away sometime soon. So the recent week has been very busy for me.

KyleF

Sorry to hear that. Family is always first. Let us know when you get back to playing with the car.

KOHV94

Hi guys, long time no see. Alot has happened since I made this thread. Sorry for not coming back and giving you feedback to what has happened to my problem. It was a simple fix though. To drive..just drive. The car had been sitting a while in storage when I got her. So me and my girl took a long drive this sunday. The stuttering stopped all of a sudden.

My bet; condensation in the fuel. Alot of it. Now all that remains is to fix the temp-sensor and get a new sender + fuelpump and I'm golden.

thank you guys for attempting to help me. I appreciate it alot.

KOHV94

Hi again guys. The stutters came back. Same thing going on. Changed the sparkplugs, plugwires and the entire distributor. Got the timing set at 10 degrees (we run 95 - 98 octane here in Norway, I wanted a higher grade.)

I can hereby say that the car is officially free from stuttering and runs buttersmooth on the entire rpm-scale.

What could've been the culprit? My bet is either plugs or the thingamajig in the distributor that sits under the rotor.

Thanks a bunch <3
-Kimo

stron3

iTrader: (2)

My 87 Z28 305 TPI sat for a while as well, and when it came out of storage I had similar issues. Everything appeared ok, but changing the plugs, wires, and rebuilding the distributor (and replacing the internals) straightened it out 100%. Sometimes it's just the basics!

babyelephant

Your problem sounds much like my 87 350 TPI behaves at the moment, which has a vacuum leak. In my case the intake manifold gasket. I’m about to order parts this weekend.

Fellow Norwegian too
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KOHV94

Yeah, I should've started on the ignition, but it just didn't seem like it? The car was idling well and all.

babyelephant; Where do you get your parts? I use Amerikanske bildeler, Usautoparts and Jans Autoshop. How did ya find out about the leak?

babyelephant

After all my DIY-wrenching I realized I didn’t want to throw in a lot of new parts without knowing what the culprit is. So I bit the lemon and paid an hour labour at my local american-car shop. Well worth it!

Most Often I order direct from Rock Auto, they have great prices and reasonable shipping cost - and AC Delco among other brands. This time I had to order some of the parts from Summit, which I have Pony Parts (Mustang shop) taking care my order and shipping. Sometimes - when I need instant parts and can’t wait for international shipping, Steinar Stolen has been helpful (20 minutes from here).

KOHV94

Ah i see! I had to send my car to a shop as well when changing the distributor, plugs and wires. The car was in for the EU-approvement anyway, so I just told em to add the hours in on the bill. I had the parts ordered beforehand, so I saved alot there. It's a tight squeeze to work on these cars lol. Kinda crap, really. I could've done it all myself, but I don't have the means, space nor "Sotradollars" to buy a proper lift since so much must be attacked from the bottom. Kinda pondering about getting an even older car. A Nova would be the bomb. Oh well, just installed a Pro 5.0 shifter today, that was a fun job!

Thanks for the tips on where to get parts! Really appreciate it!

KOHV94

Update long overdue and whatnot.

After fiddling with the car on & off for some years and learning a boatload stuff along the way I finally figured ot out. Harmonic balancer had a slipped timing-mark so the mark was far too advanced by 10° or so. Set a new mark at tdc and set it to 8°. Purrs like a kitten and all issues gone. Ordered a new one and gonna install it when it's here.

Unloaded parts cannon along the way so most sensors, ignition-related and fuel related & dohickeys are golden.

Figured I'd come back and perhaps help some poor dude/dudette if they stumble across this thread.

And no, did not get a Nova as my last post stated I would, I'm keeping this car lol.