Hi all,

89 firebird, 305 tpi manual, 50k miles. Just looking for a little direction because I am a bit overwhelmed by the sheer amount of codes. Basically the only symptom I have here is hard starting. The car tends to cough a bit like it's only catching on a few cylinders and then fire to life and settle into a nice steady idle. Driveability is fine, seems to have good power. I'd say pretty not great mileage, but I can't really tell what "good" is since I've only had the car a month, and I am tending to drive mostly in town and spiritedly. So far I've done the following:

New d3 injectors
all new o rings on the rail
Cleaned maf
New O2 sensor,
New coil, cap and rotor

To be honest I would not be pursuing this save for the ses light which came on after I cleaned the Maf. My guess was that it had never been cleaned in it's 50,000 mile life and when the readings changed drastically the delta between O2 and Maf was too far off. New O2 so far seems to have solved the ses issue, but hard starting is still there. So now I want to figure out what is going on here.

Next on my troubleshooting list is setting the base timing. Once I do that, where do I go? I'm really hesitating to get a new ecm and prom as the car is bone stock and I just can't see the car running so well with faulty ecm. However it seems the above codes are pointing to those as likely culprits. Anything I am missing here? Thanks in advance for your expertise.

 

With the code 51 and I think code 61 is bogus I’d replace the ecm

 

You think the prom/memcal is probably OK? I understand that the ECUs tend to get bad solder joints after some time, but does this typically affect the memcals as well? thanks for your response.

 

I’d bet ecm over a memcal issue

 

Final question, are any of the ECMs interchangeable? looks like 1227165/cardone 776571 is on intergalactic backorder. Is there any other known source besides Amazon/Rockauto/cardone/summit?

 

The superseded numbers for refurbished 165 ecms are 77-7165, 16198259 and 88999194. Might check eBay too.

https://www.ebay.com/itm/22488490677...mis&media=COPY

 

Did you clear the codes and see which ones come back? Some of those codes could be attributed to a missing memcal and/or disconnecting the EST connector to set timing...

 

So relevant question I guess, the manual says that all you need to do to clear codes is unplug ecm power at the battery, which I've done multiple times and all the same stuff keeps coming back like the O2. Did I miss a step? Again, car runs great. I just took out the current ecm to see which one it was and found out it is a reman of some flavor. Looks pristine. Lubed all the connections with dialectic and it's running better than ever. No hesitation firing up.

 

From RockAuto you can sign-in for notification when available. It took a week to get notified. I immediately bought it and it went back order after. I did it road side with my phone as soon as I got the email. Worth the try.