I swapped out the stock 305 for a 350 and now that i have it back together with all the stock tpi,injectors,prom etc the car pings very bad under acceleration and idles very badly. Is this because of the stock 305 injectors-prom? its a mass air car and a 5spd. What can i do. It seems like the injector/prom is the problem. How do i fix this?

 

I think your first priority should be the following:
1. Get bigger injectors and an AFPR
2. Get a knock sensor for a 350.
3. Verify your timing.

This should remedy the situation.

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also check for vac leaks for that bad idle

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350, Comp 262, Edelbrock Performer intake 600 cfm carb and exhaust, headers

 

My '88 Formula was done this same way and I've not experienced ANY of these problems you're describing. It's never balked at being fed by 19#/hr. (305) injectors vs. 22#/hr. units nor the fact that I'm running the stock 305 chip in the ECM. I also ran it for sometime with the old 305's knock sensor before I realized they were different.

I would look elsewhere first and vacuum is a REAL good starting point. Then make sure your timing is in order and being adjusted by the ECM as needed.

Good luck,
Paul

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'88 Formula (now) 355/T-5 w/120K
'83 Firebird (now) 305 H.O. & 4 speed slush box w/207K and looking for 300K with a MAJOR attitude

 

My car is also a stock T-5 car and does not use an AFPR.

I plan on having a used set (already got) of 22#/hr. units cleaned and flow matched by Cruzin' Performance to swap in there at some point.

The only problem I've got with mine is a vibration which I believe is a bad harmonic balancer or possibly the weight of the flywheel. Have you experienced this? If not, did you re-use the stock flywheel and what kind of a balancer are you running? I'm assuming too that your engine is an externally balanced "L98" one-piece rear main seal SBC.

I'd be interested in knowing.

Talk to you later,
Paul

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'88 Formula (now) 355/T-5 w/120K
'83 Firebird (now) 305 H.O. & 4 speed slush box w/207K and looking for 300K with a MAJOR attitude

 

The spark advance curve map is designed to accomodate EGR. If your EGR isn't hooked up and operating, it WILL ping like crazy! Either get the EGR working or go with a normal HEI ignition and standard carb.

Also, are all of the sensors giving the computer the info it's expecting? If the computer goes into default, or limp-home mode, the mixture and timing will be fixed and the car will ping for various reasons.

 

I would definatley agree with jrr. EGR can make your car run like horse sh_t if not operating properly.

 

I third that , I recently put a new intake on my car and I put the EGR lines on backwards and thought the Timing was screwed up it idles so bad. You could try plugging the EGR lines to just see if that elimantes the bad idle. Also check for vaacumn leaks in other ares to. The stock plastic vacumn lines are notorious for crumbling/cracking when they are old.

You need to get a 350 ESC module (Electronic Spark Control) also to go along with the 350 knock sensor.


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1988 TA 300+hp 350 w/ TBI and Holley TB unit, Holley projection intake,
WC T-5, 3.42 gears w/ Auburn posi. MSD 6A, edelbrock TES headers, dynomax 3" cat and cat-back system, ACCEL coil, polyurethane bushings all around, aluminum driveshaft, Mr. Gasket open air cleaner.

1993 S-10 w/ 4.3L V6 TBI, slightly bigger cam, Mild polish job and 3 angle valve job on heads, Edlebrock TES headers, Dynomax cat back, MSD 6A, ADS chip

2000 Kawasaki KX 125

 

don't let people tell ya that you need bigger injectors, you don't until you start maxing out your duty cycles. besides, injector size doesnt have anything to do with how you car idles. i am goin to agree with the EGR, cause they do cause alot of problems that will have you guessing for days. i am still using the 305 ESC and knock, but it is probably a good idea to change them anyways. my knock sensor gets alittle retard happy at times,and kills the power.

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87 iroc-z 355 TPI 5 spd. 51006 SLP cam adv. 4* (106.5* centerline)
hypertech stage II chip/ 160* stat./ Airfoil, accel AFPR
19# injectors, ported plenum and runners. 9.8:1 compression
stock heads, pocket ported, 1.94 int., unshrouded.
stock exhaust manifolds and y pipe! hopefully soon to change
3.45 rear (stock)
Flowmaster, K&N w/ hacked airbox/removed MAF screens
14.38@100mph 2.2 60'

 

The ESC module is the same on a 305 as it is on a 350. I confirmed this with my local GM dealer.

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'88 Formula (now) 355/T-5 w/120K
'83 Firebird (now) 305 H.O. & 4 speed slush box w/207K and looking for 300K with a MAJOR attitude