Ok here goes, After installing the set up the car initialy didn't even idle with the mail order tune I had installed, we fixed that, replaced plugs, replaced O2 sensors, the thing would still not idle with out sounding like a cylinder was going to come out the bottom. above idle it runs fine, alittle rough but ok. Had a dyno tune done and had to REDUCE timing at WOT to gain 20 hp and 30FPTQ. 13.8 A/f. awsome, but it still wont idle.

the best way I can explain it is it stumbles, and looses vacuum in drive with ac on. iac counts are pegged at 160, with it in park or neutral and no ac on the iac counts are less than 5. it idles at 900-1200.

at constant speed from idle to 3000 it backfires and pops, in the parking lot or on the road. I'd like to see some of your tables or entire tunes if possible.

by reducing the closed tps advance it smoothes out somewhat but still does it. I am at my wits end.

this is a 93 so Speed Density, I have an emulator so tuning is not a problem. I can post any info on the tune or logs.

WOT works like a champ, over 410 hp, but I cant drive in traffic.....
closed tps Idle timing

4800 34.00
4400 34.00
4000 34.00
3600 34.00
3200 34.00
2800 34.00
2400 24.00
2000 24.00
1600 24.00
1200 20.00
800 17.00
400 17.00
0 0.00

 

Check and make sure you don't have a plug wire crossed. I had this happen once where the wires go under the alternator. I had 2 and 4 crossed where you couldn't see. Had the syptoms like you describe. Just something to check.

 

thats pretty interesting, and it ran fine at other rpms?

 

Interestingly enough yes, it ran kinda rough but seemed to clear up. I had just put the motor in and was chasing all the little bug, and was thinging it was everything else, readjusted the vlaves 15 times ect..

I was pissed and happy when I found it.

 

I'm running 26 deg timing at idle. Try bumping 800-1200 to 26 and 1600-2400 upto 28-30. Are you getting knock retard under 3000rpms?

 

would and Opti problem only manifest it self at lower rpms

 

And is there ANY way to diagnose a faulty or failing opti with out codes.....

 

Well if the 3.2 cam is nuttier than the LE2 (CompCams 3111/3111 on a 107 lobe sep) then I can tell you that your problem is lobe separation and vacuum.

If you have none then it will run fairly crappy below 2500-3000rpm no matter what you do. I spent 2 years on a '96 Vette trying to mask the inevitable (LE2 heads/cam). I was pretty successful (A/C on.. no stumble, no hesitation on heavy braking... never died).

But after awhile you go... Hey, this still sucks.. my exhaust stinks, I still get odd low rpm dead cylinders ('cause the fuel pressure regulator goes full fuel on what it thinks is max MAP.. i.e. no vacuum.. and the PCM can't quite compensate).

Don't get me wrong.. If you've got steep gears and hit WOT as a matter of fact then these type of cams work great. They make terrific power but kinda suck to drive at less than 100%.

 

i know what you mean dann i have the same cam in my 383 le3.2 with the same specs and experience the same problem backfires iv learned by now how to drive it by now but every once in a while its like god when is this thing gonna backfire again but seems like vacuum is the issue here

 

Did you ever get this problem fixed? I stumbled across this thread and noticed how retarded (pun intended ) that closed tps timing table is. With a cam like that, you need 30*+ of timing at idle to see the vacuum you're looking for. The rule of thumb is to keep advancing idle timing until the car is pulling the most vacuum (lowest MAP reading) at idle. Think about it, how is the car supposed to idle and support an AC with 17* of timing. I'd start with 28*@ 800, 30*@ 1200, and 32*@ 1600 and just keep adjusting the 800 and 1200 rpm timing until you've found where it's pulling the most vacuum.

 

well i never see 800 rpm anyway, but i am still messing with timing. it still shows signs of a dead cylinder or miss. Oh is it normal to see 270 deg withan Ir temp gauge on the outer cylenders.. 1 2 7 8 and 320 to 380 on inners, 3 4 5 6? Im just trying to rule out injectors vs tune vs opti.....and the saga continues

 

Gee willickers I'm having all the same problems only thing is I only have 82 miles on it.

 

+1 similar symptoms here, but only 60 miles

 

It doesn't matter if you see 800 rpm. The table is setup in 400 rpm increments and the PCM will interpolate the values between 800-1200 rpm (ie car is idling at 1000 rpm) to get the correct timing value. So, adjust that one as well. Also, I would imagine the outer cylinders would run a little cooler because of the extra exposed area. Now, 50-100* I'm not sure about. You may want to start another thread inquiring about the temperature difference and what can cause it.