O.K. guys please bear with me because I really don't know what to do from here and it's driving me crazy. I have the 350 TPI and it idles rough, or shakes, especially when it's warmed up, but sometimes as soon as I start it. Any engine speed up to 3,000 RPM is pretty rough, and sometimes it hesitates and then takes off without shifting gears, in third gear. It has died a couple times when I put it in gear, especially reverse, but it idles rough in park or neutral also. The tach needle kind of "ratchets" up sometimes (50-100RPM) when I accelerate, and the voltage gauge drops down to 9 when I idle and use accessories like the windows, and even flickers when I use turn signals. It has a loss of power sometimes, but this seems intermittent. The computer has set no trouble codes.

I have replaced the distributor cap (Accel), rotor, plugs, wires, coil, fuel filter, oxygen sensor, 195o thermostat, CTS and air filters. The MAP sensor checks out good, and so does the TPS with a Fluke. All fuel injectors have a cold resistance of 15.9 ohms, and I can hear 'em all clicking with a stethoscope. The car only has 40,000 miles on it. No noticeable exhaust smoke and the old plugs looked pretty normal. No broken valve springs, bent pushrods, etc. I DID remove the air pump for more space under the hood to work with. I had it hooked up to a scanner at the dealership and they couldn't find anything, but I know d-mn well something is wrong. It really feels like the car is only firing on 6 cylinders at times. I'm sorry this is so long, but I wanted to give you as much info as possible. Thank you for your time, and please try to help me.

 

it's pretty common for the voltage to drop at idle. i'd run a compression test if you've not done that and check the vacumn, or check for a leak. seems you've done everything else and replaced all the common problem parts.

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-=ICON MOTORSPORTS=-

[This message has been edited by ede (edited October 07, 2000).]

 

Thanks for reading all that crap, man! I sprayed some carb cleaner around everything several times checking for vacuum leaks, and I don't own a compression tester but the heads look good and I was assuming the rings on a 40,000 mile motor that has been maintained are good too. Do you think the IAC motor could cause it to run rough all the way to 3,000 RPM and lose power? I haven't checked it yet.

 

I know this is long, but anyone got any suggestions? Vader?

 

Anyone? Sorry it's so long.

 

Here's a check list from the 87 Camaro Shop Manual
'Rough, unstable, or incorrect idle, stalling'

1 Visual Inspection
ECM Grounds; vacuum hoses; air leaks at throttle body mounting and intake manifold; air leaks between MAF and throttle body; ignition wires for proper routing, cracking, carbon tracking; wiring for proper connections, pinches, and cuts.

2 Throttle linkage for sticking or binding.

3 Iginition timing.

4 ECM ground curcuits.

5 IAC system.

6 Generator output. Replace if <9 or >16 volts.

7 Park / Neutral switch curcuit.

8 Injector balance.

9 PCV valve.

10 Emission Control System.

11 A/C signal to ECM terminal "B8". Scan tool should indicate a/c is being requested whenever a/c is selected and the pressure cycling switch is closed.

12 AIR system. There should be no AIR to ports while in closed loop.

13 Run a cylinder compression check.

14 Inspect oxygen sensor for silicon contamination from fuel, or use of improper RTV sealant. The sensor will have a white, powdery coating, and will result in a high but false signal (rich exhaust indication). The ECM will then reduce the amount of fuel delivered to the engine, causing a severe drivability problem.

15 Check for fuel in pressure regulator hose. If present replace regulator assembly.

16 Check ignition system: wires, plugs, rotor, etc.

17 Check for loose or damaged air duct between MAF and throttle body.

18 Disconnect MAF sensor and if condition is corrected replace sensor.

19 Clean injectors.


This is pretty much verbatim out of the manual. By your initial post it looks like you've done most of these things, but I didn't want to leave anything out, and if you have a MAP sensor, the MAF info doesn't apply.

 

Thanks a bunch, man! I'm going to finish up my clean up of the ignition system and if she still idles like that I can use this list to do the things I haven't already done. I appreciate you taking the time to do that.

 

sounds like how my '86 IROC was acting when the EGR was starting to take a dump... could be a vacuum leak too...

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'86 IROC-Z 305/auto with no cat, performance chip, shift kit, and 4.11s
'87 IROC-Z factory loaded with every option, 84,000 miles

Webmaster: www.IROC-Z.org

 

I kinda suspected the EGR system some too, but I just didn't want to pull the plenum unless I have to. Is it that bad to fix the EGR system on a 350 TPI? I may look at that next after I finish the distributor problems. Thanks for reminding me of that!

 

it's a biatch to change... expect your car to be gone for almost a week.. when you need to do is take off the plenum, get the number off the top and goto GM and get the EGR.. get a new MAT sensor too and clean up your throttle body and plenum with carb cleaner.. don't bother with AutoZone or Pep Boys or something.. those idiots sent me the wrong EGR 2 times before I just went to GM and got the right one for 75 bucks...

as well, when it's all torn down, change as many vacuum lines as you can, cuz that's the time to do it

good luck dude,
Colin

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'86 IROC-Z 305/auto with no cat, performance chip, shift kit, and 4.11s
'87 IROC-Z factory loaded with every option, 84,000 miles

Webmaster: www.IROC-Z.org

 

Thanks for the tips...I have been know to be an Auto Zone and Advance junkie. Looks like I have a lot of fun in store for the next couple weekends to get that car running right...after my Blazer gets a new intake and exhaust of course!