Tims91RS

I am almost complete with the swap. The engine was running fine with the 305 chip after the swap. I installed the 350 chip in the Camaro computer(746) and it does not want to idle(rough). The engine currently has the 350 knock sensor and injectors in it. I could not find where the ESC module was located? Would that have any effect on idle? It was a completely stock 350 motor from a 90 Caprice police car with the chip, computer (746) and injectors. Any help or suggestions?

Tims91RS

ttt

Saber

iTrader: (2)

The Esc is on your firewall, on the drivers side. I changed mine with a 350 ESC when i put in my 350 Knock sensor. There is varying info on weather or not you even need to do this, and im throwing a knock sensor code ever once and a while since i swapped things in. i dont think an ESC will effect idle. My car would not idle after my swap, turned out to be a bad CTS, than shortly after the IAC and TPS went. You can adjust your idle on the TBI unit itself with a torx screw, id try that first after checking the IAC and the TPS. Sometimes sensors just dont work with new stuff.

Tims91RS

Where is the CTS(coolant temp sensor) i assume. Would it idle perfectly with the 305 chip though even if it was bad. I have not driven the car yet. Is the CTS located on the drivers side head?

Fast355

iTrader: (2)

CTS is on the front of the intake manifold, in the water crossover passage, very near the thermostat housing. The sensor in the head is for the cooling fan(s).

RBob

iTrader: (1)

The coolant sensor in the drivers side head (US side of the road) is for the dash gauge. The cooling fan sensor is in the passenger side head between # 6 & 8 plugs.

RBob.

Ronny

iTrader: (1)

Was the donor engine running well B4 the swap?

Is the injector spray conical and steady??

Spark wires and or distributor installed correctly?

does the CE light work?

Saber

iTrader: (2)

Can you throw the 305 chip back on there and will it run fine with it?

Boogie123

I did this swap on my 91 rs and had the same problem. Ran rich as hell. I used a 350 caprice chip from motervation which was probably my problem and might be yours. Never tried another chip tho thats just what I think the problem was.

Jono4820

iTrader: (1)

I also did this swap and had identical problem. I originally put the copcar chip in my camaro ecm. Car idled rough and I had a check engine light. I put the caprice chip back in the caprice ecm and installed the caprice ecm and chip in the camaro.....problem soved!

Tims91RS

was the cop car ecm the same part number as the camaro? mine is. To pervious post the spray pattern is fine, the distributor is installed properly and I heard the engine run in the caprice it idled and revved fine. Thanks, tim

Ronny

iTrader: (1)

8746 used F and B body(caprice) for TBI 1989-1992 L03 and L05. 1988 F used 8063.

Jono4820

iTrader: (1)

After the engine swap, I had swapped the chips (92 caprice 9c1 to 91 camaro rs) and the car ran like crap. I swapped ecm's (with correct corresponding chips, and the car runs great. This leads me to believe that the ecms are slightly different somehow.

Tims91RS

I'll try swapping in the caprice ecm/chip this weekend. I saw in the forum that if the computer was a 746 that all you needed was the chip so I did not try the computer initially. Thanks for the help. I'll post the results when I swap them. Is the ESC module necessary from the 350 also?

Ronny

iTrader: (1)

ESC module is recommended. I believe it affects the ability to have spark retard when the sensor hears knock. 305 vs 350 must be close on harmonics. Not sure what the result may be. More or less sensitivity.

Ronny

iTrader: (1)

It would be interesting to know what the differenced are between ECUs. GM 1988-1989 used like 5 different ECUs Obviously some used port injection vs TBI. some supported VATS. My old 7747 id not support intake air sensor whil;e 8746 did. Emmision sensors/devices may vary.

If explained to me I still may not compredo.

Tims91RS

This weekend I swapped in the 350 computer, chip and ESC module and the car still searches for an idle when completely warmed up. It almost stalls then the idle picks up, repeatedly. It revs up fine. I set the base timing which helped a bit. The throttle body was rebuilt by myself when it was on the 305, I only swapped the injectors from the 350. There was a code 43 in the computer when I checked it. Any other suggestions?

gregs78cam

My situation is slightly different but the problem is just about identical. Two weeks ago I swapped a tbi 350 from a 90 G10 van ('7747) into my 74 1/2Ton plowtruck. It is doing exactly what yours is. It surges at idle in park and neutral, but idles just fine in gear. It is also throwing a code 43. And it does not always like to start right up, but I think that may be partially because of the subzero temps we are having now. I can unplug the IAC and it still does it. Keep us informed of what fixes the problem.

Ronny

iTrader: (1)

A datalog of the surge would be telling. I can explain what I saw when I experienced similar event during my tuning effors.

1. I saw timing change during surge event. With a surge the cells around desired RPM(SA table had varing advnaces I flattenned them so if a SA cell RPM/MAP changed it saw the same commanded SA.

2. I witnessed A/F ratio changes during event on WB. It went lean. so I commanded OL idle without feed back from NB02 sensor and then enrichened those OL table cells I was idleing in

3. I saw IAC counts swing. I commanded zero IAC steps at idle RPM and set the idle speed with throttle stop screw.

4. I also reduced proportional gains but that has more to do with use of a 7.4L injector at higher fuel pressure. You may not need that.

91 RS Drop Top

When I bought my car it already had a 350 swapped in. It acted exactly like you described above. I never actually found the probably, but I slowly got a FULL tune up done peice by peice (got interrupted with a tour in Afghanistan). I'm not sure exactly which item solved it, but it idles great now. Tune-ups are like that. More than the sum of their parts sometimes.

So if you haven't already try all of the following:
Air Filter
breather
PCV
plugs
wires
cap rotor
timing
fuel filter
check for vaccum leaks
tps
Full seafoam treatment

Maybe O2 sensor

I wouldn't go chasing expensive gremlins until all that has been accomplished. Good luck