If you all remember i had the problem with the car not wanting to react over 3500 rpms. well now that problem comes and goes, but just when it acts normal it hesistates for a second at 4500 rpms. when i would shut my car down, it would diesel for maybe a second. so i went to start my car today and it took about four minutes of off and on cranking before it started. then when it started my idle speed was way too low (it had been for days), it was 500 in drive and about 600 in park. it would lope quite a bit, so i turned the idle screw up a little and now it idles at 750-800 in park, and 600 in drive. i adjusted my choke a little more. well now the dieseling problem has gotten bad! ive had quite a bit of carbon buildup as the smog test showed, so my dad sprayed a bit of water in the primaries as i held the engine at 2500 rpm. it still dieseled after that, so i now shut it off in drive till i figure things out. its burning a little rich. does anyone have any suggestions to cure my symptoms? thanks

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1987 LG4 Camaro z28
Mods- 80 series flowmaster, k&n filtercharger, open air element, cat pipe delete, 180* stat, edelbrock performer intake, msd blaster coil, ascd big block hood, panasonic cd player, rockford everything else.

 

sorry about the big sig pic.... im working on it.....

 

Thats an awesome hood, what one is it?

And why oh why is it parked next to a MUSTANG!

Anyway, to your problems...

"it's running a little rich" ... That give you a clue? Fix everything you can first.

When was the last time you did a tune up?

 

thanks its the ascd big block hood. it fit really nicely, i got it from year one. also, that is my roomates mustang, its a beauty! anyways, i changed the plugs about 2k miles ago to bosch platinums. i changed the cap, rotor, wires, coil about 700 miles ago. i changed the egr and o2 sensor about 1500 miles ago. no codes have been thrown. i currently use 91 octane. i think that these problems may be due to a faulty ignition system. my car never starts on the first crank.

[This message has been edited by z28onTweenkies (edited December 02, 2001).]

 

I am not real up to date on Carbs but do you think you need a complete rebuild on the Carb?


Brian

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1989 Camaro RS

305 .030 over Hydro Pistons
Vortech heads milled to 58cc...Performer RPM intake....LT4 cam..Crane Gold rockers...FastChip custom chip...ALum. Driveshaft...3.73 gears with Posi...underdrive pullys...Rebuilt 700R4 with Vette Servo and B&M shift Kit...MSD ignition...A/C Delete No SMOG junk....1997 SS leather interior...B&M Shifter... Ultimate TBI mods...14X3 K&N open Element Non-Drop...Hooker headers....3" exhaust with Flowmaster Cross flow 16X8 Wheels from 97 RS Spohn LCA's Spohn Panhard Bar..LETS PLAY FORD!!

www.geocities.com/feltsb

 

What's the base timing set at? Could be a bit retarded.

Oh, and to the guy who asked about why the 'Stang in the pic...well, take a closer look and you'll notice it's garbage day

 

i thought if my ignition timing was too far advanced that it would cause the diesel effect. its set at zero right now, and i think i have enough mods to boost it up a little, i guess i will have to play with it a little. what is the likelihood that a spark plug could be the culprit?

 

Z28,

Dieseling (run-on) is most commonly caused by a hot spot in the combustion chambers. This can be carbon coking on a head, piston, or valve, or could be a hot spark plug. What heat range plugs are you running?

The carbon coking should have been helped somewhat by the water injection/cleaning, but it takes quite a bit of water for a pretty long time to clean up heavy carbon deposits.

The hot spot in the chambers can also be worsened by a lean mixture, excesive timing retard or advance (usually retard) or very high fuel volatility (low octane). Another factor that can contribute to dieseling is low idle speed and lean mixture, which is worsened if the engine is allowed to idle for extended periods before shutting off.

Worn throttle plates or the throttle shaft can also contribute, since the misalignment can cause a lean mixture in one bank of the intake.

On rare occasions, the ignition may not completely shut off, allowing some weakened spark to continue to fire the engine. This can be true if the alternator wiring has been modified, or if an aftermarket ignition is installed incorrectly and the alternator is not switched out of the circuit (allowing it to auto-generate) when the ignition is shut off. Any leakage current to the field windings through the ALT lamp in the dash or an aftermarket ammeter/voltmeter/ignition system could cause this.

My guesses are that you could try cleaning again with GM top cylinder cleaner;

Remove and check the spark plugs for signs of heat damage and blistering of the insulators, and recheck the part number when you do. Try a colder heat range by one index point to see if that helps;

Reset the timing, making certain it is at least at the factory minimum advance. A few degrees more advance shouldn't hurt this situation, and might help if the timing marks are not perfect. Remeber, retarded timing, lean mixture, and low idle will contribute heavily toward dieseling;

Check the idle mixture to be sure you aren't excesively lean. Vacuum leaks can also cause a lean mixture at idle that might not be as apparent at part and full throttle loads;

If you still have a functioning ECM, oxygen sensor, and the stock E4ME Rochester carb, make sure the mixture control solenoid is working and adjusted correctly. That can affect idle quality a lot, as well as the possible dieseling;

You might also want to consider checking the EGR system to make sure it functions properly. Lack of EGR can heat up the chambers pretty well.

That should keep you busy tomorrow morning...

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Later,
Vader
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If you want to beat the World, it might reach up and pull you down...
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