yes I'm serious, in the attempt to get someone that actually knows allot to help me through this. no amateurs. I've pretty much narrowed it down, the spark plugs are pitch black on one side then fade to white on the other side, no ash deposits, so I assume it's running lean, now the question is WHY?! -all spark plugs are this way- This is what the car does, it runs fine for the first 5 minutes. as the engine warms up it gradually starts running worse then misfires and knocks at idle (around 550rpm). If I rev it, it clears out and idles fine for a couple seconds then back to misfiring. If I rev to 3000rpm(or any rpm) and hold, it revs up semi-fine with slight misfire like it's starving for fuel, holds the rpm fine for about 5 seconds then starts misfiring. When it's at idle and misfiring, if I keep "pumping" the TPS sensor (but not the throttle) it runs fine. If I press down and hold the TPS sensor it does the same thing as holding the engine at 3000rpm. Fuel pressure is 38psi at idle, 48psi at WOT (afpr). If I blip the throttle the pressure will go up, then drop to 35psi then slowly pick up to 38psi and starts idling like crap. When I shut off the car, the fuel pressure drops rapidly. Same after I turn the key to 'run' and the pump primes itself, it will drop rapidly after the pump turns off. The fuel pump is a brand new Edelbrock in-tank from summitracing. Everything else is new also, I mean -everything- all the way to the prom, dizzy, injectors and ESC module. I had a problem before this that had reversed symptoms, the engine idled fine but would misfire when I revved it, I replaced the ECM and now the car does this, the car misfires at idle but will rev way better. my questions; what does it mean when I pump the TPS and it runs better? Could the new ECM be faulty? Can the fuel pump be bad even though its fuel pressure is normal??

the fuel pump could be weak...even thought the pressure is up....but the pressure at idle should be 43.5 lbs....not 38.....that may be somewhere to start.....pushing down on the tps without hitting the throttle tricks the computer to add more fuel....and it runs better....so maybe it's running lean.....just my thought, maybe somewhere to start...and i'm not a amatuer for sure....

hah, I've posted my problem on here 4 times, talked to master mechanics and other tpi specialists and no one said anything about it supposed to be at 43psi at idle (i've searched but never found anything).
That actually clears up allot, because when the engine is cold it adds more fuel. I'm going to go ahead and order a new fuel pump tomorrow and see what happens, I figure it's either that or the ECM.

yeah.....I'm about 99.9 percent sure it's supposed to be 43.5 psi...that's what I have mine set too....and camaro fuel pumps are a common problem...I've done 4 since I've owned my car....so get a good one..not the cheapest on the parts store has...the best factor OEM part I used was a bosch pump....worked great...

How old is the Fuel pressure regulator?

agreed, might check that too.....and also fuel filter...I change mine with every oil change....

regulator is stock, It was in good condition when I installed the afpr and still is, i checked if it was leaking.

Fuel filter has been replaced twice, gas tank was washed, flushed and re-sealed with POR-15 tank sealer, clean as a whistle. Fuel lines were also flushed. Injectors I pulled out before had no debris in the filter baskets.

i mean not the regulator, the diaphragm...

yeah try pump couldnt hurt especially if its older

But why are plugs on one side running rich and plugs on the other side running lean?

Has the engine been apart? Manifold swap etc? Are the intake manifold bolts tight? I'd suspect a leaking intake gasket on one side. Leaking enough to cause a vaccum leak but not leaking enough for a coolant leak.

There's a number of ways to find out if there's a suction leak. Best method I've found is to use a propane bottle. Unscrew the nozzle end off and install a rubber hose over the tube. This allows you to direct the propane gas into a tight area. With the engine running, move the rubber hose over the intake ports. If the idle picks up, the engine is sucking in the propane.

boy look at that slow car above me..all that smoke and still cant get pass the sign...lol



might need to recalibrate the tps sensor haynes manual tells you how to

I would change out the Diaphragm. if you still have the stock regulator, try putting it back on for the test. I had a friend who had this same problem with his BBK (I seem to hear that a lot about the BBk) regulator. We chased the problem for months and then, for $hits and giggles, we tried his stock FPR with a new diaphragm and Voila, problem solved, LOL.

This bit sounds like an injector is stuck open. Pressure should be lower at idle with the vacuum line connected. It should go to 43psi when disconnected at idle.

It would not be a bad idea to use a scan tool to check the TPS reading and have a look at what the ECM is being told. The TPS could be dodgy too.

Changing the fuel pump is a drag in these cars as i'm sure you all know..... it sounds to me that the car is running like crap once it goes into closed loop.

If it's a fuel problem, I'd say your pressure is fine... i've never been able to get my pressure above 40psi even with an adjustable FPR.

I really doubt your problem is the pump, fuel filter, regulator.... it might be something electrical... i wish there was a way to diagnose these cars better than swapping parts, sorry if this didnt help

just change the plugs and try it it might be fouled on that side. change them all and see if there is a difference if not then i would check you're ecm if its calibrating right on ur fuel/air ratio.

on another note. fuel filter could be clogged. it could be few things. hope you find out. gl.

I agree here, the one bank should not be rich while the other side is lean. CHeck your fuel injectors too to make sure you dont have any that are clogged/stuck open etc on that rich bank

CHeck the distributor/ignition module to make sure its not screwed up and messing up the timing.

make sure the o2 sensor is new and working. Idling ok while heating up, then rough poor idle when warm shows closed loop operation is out of wack. Usually o2 sensor but can be MAF related too

Last, the ECM may very well be screwed up

I think he means that the plug tips are half black and half white on each one, not black on one bank and white on the other

not to be mean, but for organization purposes
Stephen87, If you could delete your own posting, snowmans, berlin's and Orr89's that would be great lol

let me clear things up more...

the spark plugs;
1 bank is not running more rich than the other. while looking at a single spark plug, it is black on one side, and as you turn it, it fades to bright white. no deposits of any kind. all spark plugs look the same.

the fuel pressure;
w/ vacuum hooked up, it reads 38psi at idle. w/o vacuum it reads 48psi at idle.

I don't have a vacuum leak, they don't cause these symptoms. but thanks for your thoughts lol

the fuel injectors;
are not leaking, I had my old injectors serviced, they came back perfect. I bought a new set of injectors which are on the car now just to make sure the old one's were not leaking.

NEW PARTS on the car;
the whole long block, fuel injectors, fuel pump, fuel filter, gas tank, MAF sensor, MAF power relay, MAF burn off relay, ECM, PROM, IAC, TPS, temperature sender to ECM, heated O2 sensor, distributor, ignitions control module, distributor cap, coil, ESC module, knock sensor, pcv, EGR is blocked off and disabled on PROM, AIR is disabled.

There is NO codes. SES light flashes once then stays illuminated when you turn the key to 'run'.

Now that I've thought about it, it can't be the fuel pump. I've tried unplugging the fuel regulator and it still runs the same when the fuel pressure is at 48psi. so that should rule out the fuel pump and the whole fuel system.

here's a datalog;

what plugs are you using? might want to change your heat range

Bosch platinum (single). I'm not sure of their heat range... I guess I could try switching to a colder spark plug....
but why would the engine idle better when I pump the TPS? If it was the spark plugs being too hot and detonating wouldn't it continue to misfire even if the TPS was being pumped? or throttle blipped?

Looking at your Winaldl screen above I noticed your O2 sensor is maxed out over 1 volt. If the sensor is good then you are extremely rich. However, under that condition I would expect to see your BLM and INT at there minimum, but they are not.

On the other hand, pumping the tps sensor should add more fuel via AE. So the fact that this makes it run better could be indicating a lean condition.

I would tend to believe the O2 sensor showing rich and go from there. I think you need to do some more data logging to find out exactly what is going on.

I'm definately no FI expert, but in the fooling around I have done I have learned one thing. A bad coolant temp sensor will play HAVOC with your plugs, O2 sensor and then run rich.
And just becuse you have a new sensor doesn't mean it's good. Our fleet FI conversion system vendor (using rebuilt early GM ecu's- aarrrgggghhhhh!) for my work has had to warranty brand new ect sensors for us. In our case, the ones that DO NOT have thread sealing compound on them were faulty from the factory. I don't know what brand they were. And, some of the NAPA replacements that didn't have the sealer worked OK.
We chased this problem for MONTHS! But we did keep getting O2 sensor codes.

1. Quote:

   Originally Posted by alvanwie Looking at your Winaldl screen above I noticed your O2 sensor is maxed out over 1 volt. If the sensor is good then you are extremely rich. However, under that condition I would expect to see your BLM and INT at there minimum, but they are not.On the other hand, pumping the tps sensor should add more fuel via AE. So the fact that this makes it run better could be indicating a lean condition.I would tend to believe the O2 sensor showing rich and go from there. I think you need to do some more data logging to find out exactly what is going on.

Could it be that the O2 sensor is bad or the wrong part and is telling the ECM that it is running rich when it's not, and causing a lean condition?

I don't know much about dataloging and don't know what to look for.

I've tried unplugging the O2 sensor while the engine is running and there was no change in the problem.

when did this problem occur?? after the engine was changed perchaps if so check to see if any wires got pinched between the engine and bellhousing
i have had similar problems with the wires pinched

Spend your $20 on a cheap multimeter and perform a hot resistance check of the injectors, disconnected, one at a time.

Then test the ground side resistance of the injector driver circuits once the engine is hot. You should read at least 500 ohms to ground forward, 1.2K reverse.

I've replaced the injectors.
had the same problem with previous injectors, even after they were professionally serviced.

to the guy above you, the car ran fine for 2 days after I got it on the road(it sat in a field for 9 years), but always had a miss like a weak injector. again, it's no the injectors.

I do not have a miss for the first minute, then the miss comes in, then it misses while revving, then it idles like crap and misfires at idle by the time the temperature rolls to around 150*

thus I think it might have something to do with closed loop.

I had a similar problem in my TBI truck. Engine ran fine at all speeds. Taking off from a stop there was no problem. If I was cruising along at 30+ mph and gently stepped on the throttle to slowly accelerate, there are a slight hesitation before it would accelerate. Drove me nuts for the longest time.

Activated the OBD-I diagnostic to watch the engine check light to see if the engine was in open or closed loop. Found out that as soon as I stepped on the throttle to give the engine more fuel, the ECM went into open loop mode.

Tracked down the problem to a bad O2 sensor ground or something like that. It wasn't screwed into the exhaust properly. Maybe it was sucking in air around the threads. Took the sensor out, cleaned everything up and reinstalled. The hesitation went away after that.

Try a different O2 sensor. Try an unheated one.

I agree with this bit. When you hit the throttle and enter AE mode, the BLM and INT gets locked at 128 (in a sense normal fueling) as the ecm leaves closed loop mode and enters open loop. Once it's over it will enter closed loop and and return to the INT and BLM value stored in memory.

Out of interest, try clearing the ecm memory by removing the fuse for a couple of minutes, reinsert the fuse and then start the car and data logging at the same time. When you hit closed loop and the ecm starts to read a rich condition, you should be able to see it start pulling fuel out of the INT. When the INT hits a certain value (about 115 maybe), it will then reduce the BLM (possibly by 2). The ecm continues to look at the INT to see if it starts to rise again. If the INT goes back to 128 then BLM will stay at its new value otherwise, BLM will continue to drop until it hits it limit which for a ARAP.bin is 108.

One thing that I'm suprised at is that it has not thrown a fault code at you yet.

In response to the no ses light....you did jumper the top right two pins on the obd 1 plug before you turned the ignition to run right? If not all you will get is a steady yellow ses light. When you jumper the pins you should get the 1- 1,1 flash three times followed by any codes in the ecu. This goes for any codes that might have happened while you were driving and when you turned the car off the light went away.

as for your issue about the stuttering idle and all, you'll have to let me know what fixes it....because i'm having the same problem. I think mine might be because my rings/internals are really worn (got a big cloud of blue smoke that comes up when i first start or sit idle for a little while)

no reason to pull codes, no ses light when the engine is running, and f.y.i. I've ran it for more than 15 minutes. I tried pulling codes before just to make sure though...


As an update to everyone else, I'm installing datalogging software again and trying to figure out how to hook it up and use it.

Is any program better for datalogging or is winaldl good enough?

I work with crap like this for a living, as an ASE master tech. Looking at your data you are showing way over rich for the 02 sensor. Its actually off the charts, the value it is displaying is out of its range of normal operation. Its obvious the car is not running as rich as it says it is, to me it seems logical to replace the o2 sensor, as it is reporting the exact opposite of what the engine condition currently is.

I can't remember how to do it. I think you jump the terminals then start the engine. On closed loop the CEL flashes slowly and in closed loop flashes quickly or something like that. It's been a few years since I last did it.

Simple easy way to know if you're in open or closed loop while driving.

from your MAT reading, it looks like it was cold when you took the data log, right?
from your screen capture, with the IAC at 141, 1300 RPM, and 16 G/S on the MAF, i would guess you had the throttle opened a little.
from that the TPS looks low, it should be around 0.54 + or - 0.04 with the throttle closed.
i've seen a small TPS adjustment make a big difference.

from what you've said, it sounds like its running lean.
i agree with ljnowell on the O2 sensor.
INT & BLM on a properly running motor should be around 128 + or - about 6.
your BLM is 120 and INT is 117, that shows the ECM is pulling fuel, which is right going by the O2 sensor.
1 volt on the O2 sensor shows the motor was very rich in that frame, if the O2 sensor isn't an A/C Delco, i wouldn't trust it.
try this, unhook the battery for a minute to clear the ECM memory, hook the battery back up and before you start it, unplug the O2 sensor.
start it up and see how it runs.

on the bosch plugs, i've seen many GMs with run problems fixed with a new set of A/C Delcos.

i've used winaldl and it works ok, but i really like TunerPro for data logging.

on the bosch plugs, i've seen many GMs with run problems fixed with a new set of A/C Delcos.




Put some good AC Delco plugs in it. I have tried bosch plugs in all of my gm vehicles and they all ran like crap, even with the platinum plugs.

Intake manifold gasket for sure! It will probably solve all your problems you described.

I bought a new O2 sensor and installed it tonight, let me explain what's going on.

when I was trying to datalog Tuesday, I couldn't get Winaldl connected. Turns out I needed a USB driver for windows Vista, But in while trying to log Tuesday I started the car and it ran like crap as soon as I started it; misfiring, idle up then down then the engine would die. It wouldn't stay running unless I gave it gas, normally it would run fine until it warmed up.

So the car instantly starts misfiring and having it's problems now, before the engine warms up.

Today, we got the datalog program connected, but it's not working properly.
When we turn the ignition to 'run' and start logging data It varies how many sensors it's pulling data from, the small box at the top that says "25" in green on the picture I supplied above is now blinking red, varying between 3-25 and blinks green at the higher numbers.
When I try to 'start' the car, WinALDL instantly stops, like it freezes.

What does that mean?

Also, what's the blue wire grounded to the firewall right above the blower motor? I could only follow it to the wire loom that feeds through the passenger fender, but it wasn't grounded; I grounded it, and the engine still ran like crap. Just wondering if it was for the ECM or something important that might have fried.

no, coolant temp shows 153*
The engine rpm is bouncing up and down
It would idle with misfire, gradually misfire down to 500rpm then bounce up to 1300 (misfire clears up), then would drop back down and start misfiring again.

i wasn't looking at the coolant temp, but the manifold air temp, it shows 56 degrees. was the weather warmer than that?
how long had the motor been running when you got that screen shot?
did you try clearing the ECM memory?

it definitely has a bad surge.

strange you could data log before replacing the O2 sensor but not now.

give TunerPro a try and see if it works for you.
you can get TunerPro here,
http://www.tunerpro.net/downloadApp.htm

you can get the definition files here,
http://www.tunerpro.net/downloadBinDefs.htm

there are also some more definition files at Moates,
http://www.moates.net/info_pages.php?pages_id=14

i can't help you with the blue wire, sorry.

Have you checked the base (initial) timing? Stock should be 6 degree BTDC.

One of my previous cars, a VN commodore with an '808 (similar to '165 ecm) with a 3.8 litre motor, once did something very similar to this. Only mine was running as rich as h*ll and went through fuel as if there was a hole in the tank! It too never threw a fault code. It even baffled the bloke who I bought it off who was a service manager for GM and was trained by the GM factory. It turned out, with the 3.8 motor, the timing sensor is mounted on the harmonic balancer (Distributorless ignition). The entire balancer had turned on the crank damaging the crank key and putting the timing way off! $600 later, it ran perfect again.

Might pay to double check the timing again as the dizzy may have slipped.

outside weather was around 50* or slightly less.
The motor had been running for about 4 minutes, long enough for the problem to occur.

I don't think it has anything to do with the O2 sensor.
I looked it up and getting partial frames of raw data mean you have a bad connection so it probably has something to do with my wire. I'll be trying to datalog it again tomorrow.

Yep, I tried clearing the memory.

Yeah, base timing is 6* btdc. I've checked it.

I'm also going to check the coil inside the distributor tomorrow.

I found out the new problem; the left bank isn't firing. I assume it's the injectors since they fire in batch. Also my headlight doors aren't lowering, so right now I'm chasing wires then I'll get back to the primary problem.

when you replaced the tps did you ever adjust it? or did you just stick it on there? with the eng off key on it should read between .54-.56 on a multi meter hooked to the top and middle wire of the tps

did you check your injector fuses? theres 2

yep, fuse was the problem.
all of my fuses are corroded and some tabs are broken.
everything is clean and in contact now.
Injectors and headlight doors work.

now back to the main problem;
I turned the fuel pressure back down to stock, runs the same, with misfiring.
I still couldn't datalog.

I ordered a new ECM, If that doesn't fix it or allow me to datalog I'm taking the car to a shop.
ECM gets here Friday the 24th.

i know its not your issue but boshe platinum plugs are junk, id switch to a set of autolight resisters

anyone got any ideas why the O2 voltage would be at 1v when the car hasn't even warmed up to NOT?

it's my 2nd brand new O2, also this one is not heated and it's mounted at the collector on long tube headers.

How did you measure your O2 voltage? Did measure this voltage using DVM at sensor, at ECM? Where did place your DVM ground lead??? If O2 is really reading 1 volt when cold this could indicate that there is a harness short between O2 circuit and another circuit. It could also be that ECM internal 450mV bias source is way off. Lastly, O2 sensor poisoning is a possibility due to antifreeze in the exhaust, excessive oil consumption or leakage, or silicone poisoning due to use of older non automotive silicone gasket sealers.

Post a close-up shot of your O2 sensor.

//RF

I data logged it. though the data logger wasn't working right, I would get readings then I wouldn't. for the split second that it did read, it read 1v. It's possible the WinALDL was wrong, but I don't see why winaldl would get that reading if the O2 wasn't sending it.

O2 sensor is a light black, looks fine with no contaminates.