I'm getting a Fuel pump relay malfunction code and a high MAP voltage. I've been having problems with the cars voltage, lights dim from 13.8v to 12.3 and it's always doing that under 1000rpm. I think it could be a bad ground on the fuel pump relay but I don't know, does this sound right? Now on to my next problem, MAP voltage being too high, what is that? I have an extra map sensor sitting right next to me so I'm going to swap that in although the readings on Diacom showed that the MAP is working. Now onto my most serious problem, black smoke!
The car is running WAY too rich and the strange thing is that I've been turning down the BPW thinking this should lean the whole system out. I was wrong, it runs rich in both closed and open loop. The only other thing I did was adjust the pump shot. I'm going to swap in the new MAP but what is up with the running SO rich? I turned the BPW down from 120 to 110 and still runs rich enough to pump out black smoke when I play with the throttle. Need sugestions, btw, I'm working with the anlu.bin as a base and I haven't touched any of the actual tables, just the constants for now.

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, Jon (350 TBI!)
91 Red My website

 

BTW, after it kicks into closed loop the BLM drops way down to like 110 and it just jumps around. The other 128 number, I....I forget the name, but that number is always either 128/9 or lower but usually not AS low as the BLM (makes sence, no engine load since I'm sitting in the parking lot).
I'm going to change the map sensor right now, hopefully this solves my running really rich problem.

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, Jon (350 TBI!)
91 Red My website

 

Okay, MAP didn't help, still getting the Fuel pump relay problem and High MAP voltage. Any ideas on where to look for a short somewhere?
This is my understanding:
Stock 89 caprice eprom, 350 with 55 injectors with not too much hp. Now my engine is a 350 with more hp and 65 injectors. Why is it running rich? I turned down the fuel pressure slightly but I didn't feel a difference, O2 is still reading high voltage most of the time. It's usually about 600-900mV and it seems to get better around 2000rpm but at idle and even around 1200rpm the thing is dog rich. I'm going to just turn the BPW down to 100 but doesn't this sound REALLY low for a 330hp engine and 65 injectors?
Question: I took out the ecm fuse, does that clear the trouble codes or do I have to disconnect the battery from under the hood?

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, Jon (350 TBI!)
91 Red My website

[This message has been edited by JPrevost (edited June 12, 2001).]

 

No ideas? Anybody know have an opinion on the situation? Anybody know what to look for when it says MAP high voltage and the sensor has already been replaced! How about the fuel pump malfunction error, this I don't understand because obviously my car runs! I know where the fuel pump relay is and it IS working so what is up with the ecm error?

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, Jon (350 TBI!)
91 Red My website

 

JPrevost, the ecm fuse by the battery will do it. I have at this time only an a/f ratio guage for what it's worth and it shows a little rich at idle and at 2000 cruise it's lean. I also thought by what I had read in previous post that the cop 350 had 65lb injectors. I wished that I could help more but you're ahead of me with programming your 350. By the way I have the same code on my chip. ANLU.

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91 RS 350TBI VORTEC HEADS EDELBROCK PERFORMER INTAKE LT4 CAM AND 1.6 ROLLERS EDELBROCK HEADERS 3' EXHAUST 5SPD 3.08 GEARS

 

The cop 350 car was with 55 injectors up until sometime in the early 90's when they went to a different ecm. Then they switched to 65 injectors. I'm thinking about getting a GM 350 injectors/pod and just run higher pressure after I get a new fuel pump. Update: Went for a drive today instead of just sitting in the parking lot! Car is running WAY rich and after it gets into closed loop it bounces REALLY bad between rich and lean. For the most part I could average all the diacom O2 voltage and it would come out to 800mv! Aren't I suposed to be around 450? Still can't figure out the darn high voltage MAP sensor but it's reporting that my vacuum is ~17 at idle/800rpm. This is with my anlu and the BPW turned down to 100. How do I go about fixing a MAP high voltage and "fuel pump relay malfunction?" I'm at a loss and I NEED to get the car running better for my 1100 mile visit home.

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, Jon (350 TBI!)
91 Red My website

 

Too bad it's not running any better JP. I received my scanner today and hope that we can get some data that we can compare that will help. I really thought that cop cars had 65lb injectors. I used the ones from one. I guess mine would be running richer if I had put my Holley on to start with having 65lb injectors on there. It seems to have good milage so far, but I'll be able to tell by Sat when I fill up to check. It runs good at steady cruise but seems to have no pump shot for accel. We'll get them figured out! Good luck!

 

That is the exact problem I was having with the stock anlu.bin, no pump shot. I adjusted my tdf file to sho ALL of the table and now when I stomp on it the whole car instantly jumps 1" taller all around .

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, Jon (350 TBI!)
91 Red My website

 

Glad to know that the pump shot adjustment helped. Is the pump shot map that you posted the picture's of what you used to correct the lag problem? If it is I might use it for a starting point.

[This message has been edited by DM91RS (edited June 15, 2001).]

 

If the lights dim I'm thinking your alternator is on its way out, Jon. You said it clears up over 1000 RPMs right?

 

The alternator I have not is a piece. I got it from some dinky shop in the middle of Penn (nowhere) when my 2 month old 140amp alternator crapped out. It did this when I was going through the tunnels on the penn turnpike (near Harrisburg), in the DARK, and in the RAIN. So when it quit, my stereo turned off, then I was confused and looked at the volt gauge...under 8...with the current conditions I decided to turn everthing off (no wipers, no lights) and the car started to miss REAL bad. This was over a year ago when they were doing construction and had NO SHOULDER to pull over. I found an emergency stop (stones) and boy was I pissed.
So I don't even know if this alternator is the right one or not, it just fits and plugged right in so I don't think there is a difference. This started about 8 months ago with the low volts drop. It's really strange because it gives 13.8-14.3v normally but then after a couple of seconds at idle the volts dip to ~12.0 and it does a nice little needle dance. It's less than 12 with my lights and indicators on.
Anyways, I figured out why my car was running like crap, turns out it was running SUPER lean. Which is strange because when you first start it up (open loop) it was running pig rich and smelled BAD. So I burned a chip called "SuperRich.bin" and that actually turned out to work well enough to get me home (just got back, 540 miles 19mpg). I have a bunch of tuning still to do but it's looking a LOT better. I noticed yesterday that my o2 wire loom was melted onto the headers . That could be turn into a big problem, it works fine now though (100-800mv jump back and forth).

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, Jon (350 TBI!)
91 Red My website

 

If i am not mistaken some of the GM ecm's compenasate for FP voltage. if that is the case then maybe your Alt is the entire problem. My GUESS is that it reads in what it calls the FP voltage & if it is low it assumes that the pressure out of it is going to be lower. if that is the case then it wants to add more Fuel for that given low voltage. AND, maybe it is adding way too much?

change the alt as you are apprehensive about it anywho, & see what gives. This is a WAG though so............

BW

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Bobalos
aka Bob W.
www.r71camaro.homestead.com
r71chevy@earthlink.net
<><

 

JP, do you have a Holley replacement TBI on there?

 

ECM reads the voltage on the lead to pump wire, sounds like a poor connection.
At syty.org they had a diagnostic chart for the MAP systems, try that first.
Too high map makes it too rich, for openers.