Ecm/Prom. problems?

Sharingan3

New Member
So I hooked up my powerlogger for the first time in months (I know, shame on me for my neglect) due to an incessant check engine light. I figure it's probably just throwing a code for an O2 sensor, but to my surprise it gives me like 8 codes ranging from O2 sensor to MAF sensor to even a code for ignition module error (I'll list all the codes later if we get that deep into this. I'm hoping this is a no-brainer quick fix). Common sense would tell me under most normal circumstances, there's no way that all these things started going wrong at once. I'm sure it COULD happen, but not likely. I have a friend who works on mid to late eighties pieces of crap for a living and after I gave him a key piece of info, he told me the computer or prom may be taking a crap. His reasoning is this: When the computer/prom starts to fail in this vintage vehicle, they are known to give a code for either too high or too low coolant temp., which mine did, even though the actual temperature (mechanical guage reads 185 degree operating temp. in concurrence with the powerlogger temperature reading) is normal. He also said to check all my grounds, which I did anyway. Besides, I would have to have a bad ground on all devices the ecm is giving a code for. Again, not likely. I was also told to twist/flex the ecm while the car is running and see if it smoothes out. I don't think it's running rough, unless it always ran like crap. Last thing: If I take it out on the highway and drive it normal, it drives fine. If I put the pedal to the floor, however, it will accelerate only to about 12 or 13 lbs. boost and hold there (almost like stock). It will keep pulling, and won't detonate or knock, but won't proceed to the 25 lbs the computer and the gate are set to. Obviously don't want to start throwing money at this one. If anyone could help, I would like very much so.

Thanks.

What the hell, here are the codes as per the Powerlogger:

34 - Mass AirFlow Sensor (MAF) reading too low
31 - Wastegate Solenoid is not connected, or has no power (which, is and does)

24 - Vehicle Speed Sensor (VSS) reading improperly
23 - Air Temperature Sensor (IAT or ATS) reading too low
22 - Throttle Positioning Sensor (TPS) reading too low
21 - Throttle Position Sensor (TPS) reading too high
15 - Coolant Temp Sensor reading too low

It also threw a code before ( not on this run) for "O2 Sensor reading too slow"

This thing was partially built and tuned at Anderson's with 435hp/590tq at the wheels with just some bolt ons and a methanol kit. Has been 11.79 @ 116 mph leaving easy due to stock axles. I hate to see it run like this. Need to figure this one out "out of shop" as I'm "out of dough". Thanks again for any help.
 

Blown&Injected

Active Member
Maybe something got messed up during the install?

Was it not running right all the time or just after the Powerlogger?

Got a different scan tool that can double check the readings?

Have you tried resetting/ killing the power to the computer?

How is the boost adjusted?
 

TurboBob

Resident mad scientist
Staff member
make sure the contact fingers are properly clean.

check the other data with the engine running and make sure it makes sense.

a few ecms have needed the PL to not be pushed on all the way.

Bob
 

bmackinnon

Active Member
Sounds like the ecm may have an intermittant bad connection somewhere. The area where the ecm is located is succeptable to moisture intrusion, and it's a fairly common problem.

Pull the ecm out and thoroughly inspect/clean the connector halves. Remove the top cover, and pull the prom out (the larger of the two) and carefully inspect/clean the pins and sockets there also. Firmly and carefully reseat the chip and connectors, making sure the chip pins don't bend, and everything is firmly seated. Bluish/greenish discoloration on the connector surfaces is an indicator of a moisture problem. Also check the integrity of the orange ecm power connector near the battery.

As far as the driving/boost conditions.... Is the car running 'properly'? FWIW, the computer doesn't 'control' boost so it's not 'set' at a given boost. Stock gate? External? Boost Controller? You'll have to provide a few more details there. Wish I had powerlogger so I could read your log.... maybe someone else can??
 

bmackinnon

Active Member
make sure the contact fingers are properly clean.

check the other data with the engine running and make sure it makes sense.

a few ecms have needed the PL to not be pushed on all the way.

Bob

+1 .... similar to the problem with Direct Scan connector being pushed too far onto the card.....
 

Sharingan3

New Member
Thanks for the input, guys. Let's see if I can answer a few of your questions and delve a little further into this. First, the powerlogger is not a new addition to the car. It's been installed properly and working great for I guess about a year now. Not to say that the PL couldn't have gotten moisture on it as well, but I didn't mean to make it sound like the PL was a catalyst for all of this if I did. With that said, I have no other instrumentation to compare tha accuracy of the PL against other than basic guages. I have killed power to the ECM...nothing. The boost is set manually via adjustment rod on the wastegate that accompanied my "out of the box" PT60, purchased through Anderson's along with Precision's Front Mount Intercooler and a 3" downpipe with testpipe and cutout (although I don't remember who makes the downpipe). I also have a bleeder by Turbo Excess for finite adjustments. Turbobob, same thing. PL is a lovely device and I doubt it is causing the complications. You and Bmackinnon seem to be on the same page with this check all the terminals idea. Let's say it was wet with no corrosion. When it dried out, wouldn't it go back to normal operation? I'm actually an electrician and know through personal experience that some electronics can just dry out and be fine, while others can't. It didn't seem like the board in the Buick was all that complicated when I had it apart to install the PL last year. Aside from corrosion on the pin terminals, what is in the board to get defected? Bmackinnon: once you accelerate away from a light, everything is fine. It reads vacuum and boost at about the respective RPM levels it did before. The Pyrometer reads the temp. it normally does at any given RPM. It feels a little more sluggish leaving a rested position than it used to. I thought this was due to my previous assumption of it only needing an O2 sensor (boy was I way off...though, it still probably needs one). And yes , my fault. I did say computer set at a boost.... meaning the gate set at a boost level and the chipset having the timing and retard data to accomodate said boost level. Good catch. Again, the gate I have is whatever Precision puts on their PT60 model turbocharger. Boost controller...yes..... and of course if the gate is adjusted by a rod, you guys already know that the actual "gate" per se is built into the downpipe....... and a lot of the reason that thing was so freakin expensive.......oh well, no use crying over pissed away mortgage funds....on with the problem solving. I eagerly await you fine gentlemans' input. As always, the help is most appreciated.
 
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