hi I have a 1991 b4c Camaro with the 350 tpi engine. I bought this car for a steal it has 130,000 miles on it. I knew when I bought it that it was idling high. I replaced the plugs, wires, cap, button, etc. While getting an inspection my buddy found a code with my coolant temp sensor. I took off the plenum and found that the coolant temp sensor wires had fallen out of the clip. I fixed that and put a new coolant temp sensor in. While driving when I first got it on the road I noticed that when I come to a stop when the engine is hot the idle surges from 700-1500.my idle in park is around 1300 btw. That's when its hot too. Anyways the previous owner replaced the intake manifold and 3 injectors (was thinking about doing other 5) and the owner before him did the egr and the iac. I have replaced the Tps. The car has loss of power too like going up a hill. Its running rich too awful gas milage. I recently bought an obd1+2 scanner and I have a bunch of codes (19-ignition system fault, 52- calibration package chip or ecm fault, a bunch of AC and cruise control codes(I figure not relavant) 64- egr flow problem or cruise control or map sensor or o2 sensor, 66- ecm computer circuit fault, etc). All in all I want my car running right and I don't know alot about these heavily sensored engines. I have no vacuum leaks. Any help is appreciated greatly.

 

Welcome Aboard!

High idle, surge, and lack of power certainly sounds like it could be a vacuum leak. it could also be various other things. While you may not have any external leaks, a vacuum leak can still exist. A leaking power brake booster, incorrect PCV valve flow or PCV connections, intake base leak (in the lifter valley), or EGR leak can be a "hidden" vacuum leak.

Since you seem to think there is an issue with the EGR valve sensed flow (based on MAP, TPS, and RPM) it might be a place to start. You can try to disable vacuum to the EGR solenoid and valve and test the theory, but that only tests the vacuum solenoid and doesn't help diagnose a stuck or damaged EGR valve pintle.

 

Try blinking your codes, Thr code numbers you put don't jive, If you are getting the code 51 , check and make sure therse not some hypertech chip installed and that the memcal is seated in the ecm. Make sure the grounds are clean and secure behind your passinger cylinder head. This sounds like its a bad 1227730 ecm though.

 

tuned performance I've tried blinking the codes and I had another Camaro it worked on but it doesn't work on this b4c that's why I bought a code scanner. And Vader the pcv valve is new and the connections are good. How would I check for these "hidden leaks"? I replaced the o2 sensor and it didn't help much. I've also tried out a new map sensor and it didn't help. My dad seems to think replacing the other 5injectors would fix it. But I don't want to spend 250 getting new ones. Thanks for the help so far.

 

I do have a hypertech chip installed!. Are those bad?

 

I have seen a couple do a bit flip and run in limp home mode. If its a piggy back you can remove it from the memcal. I have salvaged hypertechs before by soldering in a dip socket and inserting in a new chip. If it was a memcal that hypertech reprogramed from gm it will have VC scratched into the side plastic.

 

the hypertech chip came right out when I took the two side things off. Should I just try to get a used ecm and chip from someone locally? The hypertech chip says 1995 on it ill look for the VC tomorrow I think I'm just going to find another ecm and use that chip in mine. The owner before me replaced the fuel pump and maybe that upgraded fuel chip the fuel pump couldn't compensate for it.. Not sure guess I'll look for an ecm.

 

does your hypertech look like this?

The stock memcal should say ANJF or AUJP

 

my chip is exactly like that and I have aujp

 

You can just install the aujp memcal, but with the ecm not blinking codes points to a bad ecm. If the malfunction indicator comes on when you turn your key on you know there is now problem with the bulb or harness for the check engine light. The next thing to check would be continuity between the aldl b and ground and a and the ecms pin e12. If that checks out good the ecm is bad.

 

 

even though my code scanner works? So I install the memcal without the chip?

 

and my ses light goes off sometimes

 

i dont have the stock aujp chip

 

did some one unsolder the chip in the memcal. Sorry I'm kinda confused you stated in post 9 you had a aujp memcal as well. All the codes you have listed above if there real should never show on a 730 ecm witch leads me to believe its a bad ecm.

 

I've never worked with these ecms I may be confused about the memcal and the chip. Clarify to me what both are. I have the ecm out (not unplugged) and I have this long blue part with the hypertech chip in it. My ecm is aujp

 

oh i think i figured it out the blue piece is the memcal and i can take the chip out and just put that memcal in.. Ill try running it without the chip in and see if it helps

 

Yes just install the long blue chip and leave out the hypertech and see how that goes. If that goes not fix your issue I'm really thinking bad ecm or ecm ground.

 

the calibration chip code went away my idle is still high ill let you know how driving it goes

 

well now when I push the medal down at idle and release it my idle will surge. Idling hot around 1200

 

You might want to set the minimum idle speed and then disconnect the battery for a while then drive it again. if you still get intermittent communication with the ecm I think its time to bite the bullet.

 

what does that diagram mean when it says back probe ecm ckt 451

 

and would a used ecm help? i dont want to spend 300 on a new one

 

circuit 451 is the black/white wire at the ecm pin E12, you can use a paper clip or safety pin to gently push in the back of the connecter to test.

 

No don't spend $300, You can get 1227730 here in the classified section they usually run 50-60 used without the memcal. Or look at rockauto.com that ecm was used in tons of 3.1L berettas and Corsicas go to your local junk yard just use your aujp memcal.

 

okay when I probe that one with the test light I get no code 12 and that says replace ecm. I guess its bad? I thought since the cars running it would be good. Maybe that hypertech chip screwed up my ecm over the years? Where can I get a matching ecm?

 

No the hypertech wouldn't mess up the ecm, there are are several numbers for your ecm there all the same ecm 77-7730, 01227730, 1227730,16198262, 16196344. The gm trouble tree is verry good information I would replace the ecm.

 

what would you reccomend I do

 

would the ecm from any 1991 Camaro work no matter what motor size?

 

I sent you a personal message yesterday, I have a known good ecm That I have loaned to another member that has had it for several months and it did not fix his issue I think he has distributor problems. I tried to contact him yesterday and am waiting for a reply to see if he would like to buy the ecm or send it back. If you would like to try it I can give you his contact information via personal message and its maybe only fair if you pay him $12 for shipping . If it works and you would like it I would sell it to you for $30. I'm not trying to push a sale on you just a option .

 

what would I have to do if replacing the ecm doesn't help

 

I don't think the code 66 even insists in that ecm odd ball codes means the ecm is faulty . Its allways good to check your ecm ground and not a bad idea to even add a ground strap to the bulk head connecting to the cylinder head. This gets removed over time bye previous owners.

 

Application: 1227730 ECM's
1987 2.0 L4 TBI “1” LL8
1988 2.0 L4 TBI “1” LL8 (early)
1987-89 2.8 V6 PFI “W” LB6 (exc. “W” body)
1988-94 3.1 V6 PFI “T” LH0 (exc. “W” body)
1990-92 5.0 V8 TPI “F” LB9
1990-92 5.7 V8 TPI “8” L98 (“F” body

 

what is the bulk head connecting to the cylinder head. Remember I'm nit a pro at this like you.

 

Bulk head is also referred to as a firewall

 

that ground wire is there. Its a ground strap. So its the ecm? Not fuel injectors, not air flow, ecm? Absolutely sure? Sorry for being paranoid I just don't want to spend 50 for something that doesn't help.

 

bad ecm would cause high idle? And rich fuel air mixture? And cause surging idle?

 

The only other test you can do is check the voltage on the serial data line on the aldl pin M it should be 4.5v-5v dc. If $50 breaks your bank take it to a shop for a second opinion or buy a fsm.

 

thanks ill let you know if a new ecm helps

 

http://www.ebay.com/itm/92-GM-3-1L-V6-A-T-ECU-ECM-1227730-BABN-See-item-description-/181134118593?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a2c6f4ec1&vxp=mtr

cheapest one I could find on the Bay

 

new ecm is in and in still having code errors looks like its time to replace the memcal?

 

Now what codes do you get? Can you do flash codes now?

 

I recently bought an obd1+2 scanner and I have a bunch of codes (19-ignition system fault, 52- calibration package chip or ecm fault, a bunch of AC and cruise control codes(I figure not relavant) 64- egr flow problem or cruise control or map sensor or o2 sensor, 66- ecm computer circuit fault, etc). All in all I want my car running right and I don't know alot about these heavily sensored engines. I have no vacuum leaks. Any help is appreciated greatly.[/QUOTE]

Are you still getting the bogus codes ?

 

still getting the bogus codes and my code 12 still does not flash.

 

Did you get a used ecm from ebay ? If you did and it came with even a v6 memcal you can install it and don't start the car but see if it will entr into field service mode. memcals very rarely fail.

 

I dont know what field service mode is but yes it came with a v6 memcal. I bought the ecm you posted on here. If the same codes are coming up with a new ecm.... It must be the memcal...

 

well I ordered a memcal well see what happens

 

If its not to late to cancel your order I am willing to check out your memcal. I can bench test it and do a file compare and may be able to salvage it.

 

ill just see what the new memcal does. If it works ill have spent 100 on fixing all this which will be okay with me.

 

Wow you must have got a heck of a deal on a memcal