[83jp]

Hey everyone.
I Just bought a 86 camaro iroc z.the car runs good as long as your moving if you come to a light and take your foot off the gas it sometimes stalls out and when you start the car the rps jump back and fourth betweenn1000 and 1500rpms.also car burns rich u can smell the gas not being burnt off properly.and the engine light come on and says its electronic spark timing.
The car came withe a 305 tpi engine but was swaped for a 350 tpi but still has computor for a 305 tpi engine.also engine has had some mechanical up grades such as a cam,etc.
any suggestions as to waht will make the car run properly.everyobe one i talk too cant give me a sure answere.
thanks in advance

[DoubleVision]

First off if the engine was swapped to a 350 from a 305 it needs the computer and chip from a 350. There's alot of difference in calibration from 45 cubic inches of difference. Next question was the injectors bumped up to 350 injectors? How bout the knock sensor? If not the knock sensor will need replaced also with a unit for a 350. Last is the cam, the computer does not like when a bigger cam is added and the computer is not remapped to know the changes. If the cam is too big that alone is one problem. Telling us what size the cam is would be of help. As for idle, check the throttle body for slack by shaking it, once these get 150,000 miles on them they are worn out. Worn throttle plates cause vacuum leaks plus the throttle position sensor to read incorrectly. If the knock sensor for the 305 is in place this could be what's throwing the ignition code. The knock sensor works off frequencey. A 305 has a bore size of 3.736 and a 350 has a bore size of 4.000 inches, so when they knock they give off different frequencey's. If the factory sensor is still in use it could be causing it to retard to timing so much the car won't run. What is the number of the code it gives?

[83jp]

Ya its a 350 with a 305 computor.i asked the guy who i bought the car fr he said he put a mild cam(not sure wht that means).and he did put bigger injecters and the throttle body is a large mouth holly throttle body.rockers with a 1.5 ratio(not sure what that means).car runs fine besides for the stalling at the light or going into drive or reverse.car has lots of power thats for sure.
so you think it needs to be chiped.and can a computor fr a 350 hook up to a wireing harness fr 305.and if it needs to be chiped i guess a performance engine shop could do that for me.

[83jp]

Im not sure what the code number was but it said electronic spark timing

[F-BIRD'88]

Ignition fault
Camshaft to big (too much overlap) confuses the TPI EFI system. (low manifold vacuum at idle)
Get a cam thats GM EFI system compatible (shorter moderate .050" duration, wide 112-114+ LSA)
low idle timing w aftermarket cam.
Stock low stall torque converter with aftermarket cam.
TH700R4 Auto trans lock up converter solenoid fault (on the valve body)

[cdminter59]

First how about checking at a auto recycler, salvage yard, what ever you want to call it. See if they have an 1987 Camaro with a 350ci to get some of the parts doublevision suggested you change. I looked up 1986 Camaro on Advance Auto Parts.com it listed the 305ci as the only engine in 1986. So find a 1987 350ci. Knock sensor, throttle body position sensor, idle speed control sensor, computer (they just plug in), They are located behind the kick panel. Throttle body. Some computers require the dealer to flash them before they will work. I would do this before I took it to anybody. You could also buy a new knock sensor from the auto parts store for a 1987 Camaro. Then disconnect the negative battery cable for a couple of minutes to reset the computer. after re-installing battery cable check for all codes again. If all else fails you could get rid of the computer and install an intake and carburetor, coil, non computer controlled distributor to see if it runs better.

[83jp]

Ya there is a 2800 stall converter in the trany now also a shift kit.so what your saying is with the after market cam you need a lower stall cobverter

[83jp]

Sorry had to read it again.so i need a smaller camshaft.big job.would it help if i got a after market chip for thr car and get it tuned?
Or maybe replace the sensors and computors like cd minter59 said probly be better to start with the basic which are the sensors and go fr there

[F-BIRD'88]

why change 10 things to patch over the one thing that is the biggest factor.
The camshaft. If it is a mild cam you don;t need big injectors etc.

It is very easy to over cam a TPI motor.
Nothing worse than having the WRONG CAM.

These TPI motors are all aboutlow and midrange torque and do not like or need a big cam with big overlap ID the camshaft.
What is the manifold vacuum at idle, rpm and idle spark timing?

The converter lock up solenoid is a common fault on th 700r4's
(stalls at a light) and if that is the fault its easy to change.

The right cam will make it run much better in all respects.
The guy sold it to you cause he bought the wrong cam and could not make it run right.
Find out what cam is in the motor or post the idle vacuum, rpm and timing at idle info.
This can give you an idea of the cam . You can also measure the lobe lift off the pushrod with a dial indicator.

[83jp]

The guy i got it fr said it was a mild cam,thats all i know.and i wouldnt know how or have the equitment to check the stuff your talking about

[83jp]

So put back the original cam and injectors?
Is there anything i can do to fix the problem without taking the camshaft and injectors like adding or upgradeing other parts so it balances out?

[83jp]

And will thee big came have any affect on the transmission for example make it over heat.etc

[F-BIRD'88]

Surely you have or can easily get a vacuum gauge.
Not that hard. You can spend waste $$$$'sss trying to patch over
a bad cam choice.

Oversized injectors Bigger than nessessary cause more problems than
nerssessary. (rich idle) usually require custom computer prom reprograming.

What is the manifold vacuum at idle? what is the idle rpm?
what is the manifold vacuum @ 1000 rpm?
This is easy to do and will tell you a ton about the cam.

You seem hell bent on making this repair more difficult and costly than required.

You will find a thousand uses for a simple manifodl vacuum gauge. its is your friend and the best $20-30 you will spend
for a tool to help you fix any car.
No computer required except the one between your ears.
Google search "vacuum gauge diagnostics" to interpret what the gauge is telling you.
This is where to start.

Chaning the camshaft on a SBC is not that hard. And if that is the cause, the cost and effort required to change it
compared to the cost and time of all this patch up fubar will be much less...

There are many many really good bolt in TPI compatable cams to choose from, including the stock GM TPI motor cam.

[F-BIRD'88]

If you are going to own a TPI car and fix it yourself you'd best bone up on simple
TPI EFI system diagnostics. Get a vacuum gauge and a volt ohm multi meter to test the sensors.
The Throttle position sensor setup is critical. If andy of the sensors are faulty it will run
like a bag of dirt. Inspect the ignition system wires, plugs, cap, rotor. No computer required

[83jp]

Ill get a vacume gage.
in the morning when i first start the car it bounces between 1000-1500rpm.at a light if it dont stall just below 1000rpms.