kopbet89c4

So I was just driving normally back from dinner and I had to make a right turn across an intersection on a full green light. So many high speed cars passing, then I got a free space with a little time before the traffic comes again. I get on it and she stalls out for half a sec when I get on it... AHHH I was thinkin I was gonna die. Then miraculously she starts back up again and goes. Pheeeeew....

Then on the usual stop sign coming back home, of course I stop. Then just a little tap on the gas till I hit 35 mph, she stalls, and this time for good. Well, tried the usual cranking while coasting and she'll start up again and die... WTF, I swear this car is gonna kill me one day. There came AAA to the rescue and towed me home like 1.5 miles to my house.

Time to take the Helms manual out and start packing my car again with tools from a timing gun to a fuel pressure gauge... But where the hell do I start if there are no codes to pull? Seriously just a code 12, nothing else. So I scanned it and tried to duplicate the problem just driving around the neighborhood.

Right as soon as the car lost power and felt like it was gonna stall out while idling at 350 rpms, I noticed these values fluctuating on my scanner:

O2 voltage: 45-65 mV
Fuel injectors pulse width: 2.2-2.6 ms
BLM: 108

Here are those same values when the car was idling normally at 650 rpms:

O2 voltage: Normal crosses, 300-600 mV
Fuel injector pulse width: 1.3-1.5 ms
BLM: 120

Could this be a bad ground problem, bad relay or intermittent open/shorted out circuit essential to the car's drivability? Connections to the battery were tight as always.

FYI: Fuel pressure is as normal as can be, 42 psi, even at the moment the car stalls. TPS voltage is right at .55 where it should be. There is spark at all times. My ICM is ok and when this car was in idiot mode idling at 350 rpms, there was still spark. What the hell????

This problem usually happens when the car sits for awhile and is cooled down, then started up, during the transistion from open to closed loop mode.

If this is a bad ground issue, where are the grounding points on my 89, aka Christine?

bogus

the FSM has all the grounding points outlined.

however, for your needs, check the area under the battery, they corrode like crazy.

also, inside the car, in the pass side kick panel.

kopbet89c4

This is so strange. This problem mimics the typical MAF problems. Stalled right after start up, giving her gas doesn't do a thing. I know its not the MAF. I can verify this because there are no codes. I'm about to give up on her. I can't even move her from the middle of the driveway to the garage.

So what the heck? EFI TPI OBD1 is supposed to be easy...

CFI-EFI

Did you ever verify the timing mark on your damper? Have you properly reset the timing? You don't need a code to make use of trouble shooting charts in the FSM. There is a section devoted to "Symptoms".

RACE ON!!!

kopbet89c4

Trust me. I've read it about 3508 times and all of my symptoms point to lack of fuel/lean exhaust, incorrect timing or bad ICM. No codes. Timing at 12 degrees feels a lot snappier on throttle than 6 degrees.

Pffff... I just took out the fuel pump and inspected it to see if it was sucking dirty or contaminated fuel. Its just fine.

I now think this is strictly an electrical problem. If I let the car idle and warm up completely to the normal operating temperature of 180 degrees, I swear I can make it reliably from Florida to California and back, provided I had a 200 gallon gas tank!

But what is making the car freak out on the warm up? What makes it stumble and stall while on part throttle with the coolant temp just 110 degrees? Its as if its getting too little fuel when cold.

Was that scan data helpful???

Well, after warming up the car to normal temp, I was able to take it around a couple of blocks. Not a miss, sag, stumble or any hint of stalling.

kopbet89c4

I noticed there are no irksome stalling problems when car is fully warmed up. Before I drove to work, I had to let her idle and warm up for 15 minutes so I can drive it reliably through town. Once that's done, I can literally drive it forever without the fear of it stalling out on me. I'm afraid there is something freaking out the ECM when the car transitions out of open loop to closed loop. Any idea what it could be?

Red Tornado

have you done any datalogging to verify that you're not on the edge of blowing up your engine?

Da Mail Man

.......i have an 88 and i had a very similar problem 2x's already.

.....the first time i replaced the ignition module and electronic spark control unit (near passenger side of heater box) at the same time and that solved the problem.

the other time was w/in the last 3 weeks when i developed a WEAK but functional fuel pump which i replaced........fyi........

kopbet89c4

Da Mail Man, I know my ICM is brand new, ever since I switched from a large cap HEI to a small cap HEI.

Never ever tampered with the ESC module yet. But if defective, wouldn't that just cause a code 43 and super sluggish performance? Don't know if it would cause stalling or not.

I even put my spare fuel pump on to see if it really was the fuel pump. My guess is that the old one was just fine. Stalls with this new one too.

Hot Rod 90, when I datalogged my car with 12 degrees of advance, there were no 3 inch rock sounds, unless the coolant temp was over 210 degrees. And with the stock 6 degrees of timing, its about the same sound at that same temp. I guess my car doesn't like running warmer that it should. My optimal coolant temps are about 180 degrees. Once up there, fully warmed up, the car runs like a champ and feels like it could drive forever, anywhere, anytime from here to Cali and back. Like I said, open loop mode is where I'm having problems with my stalling. I know it can't be the tune. With my current tune, my drag strip performance was astonishing for just an intake swap.

jcsr72

Wow, deja vu. Sounds like Christine MAY have an intermitent faulty fuel pump relay. I had the SAME symptoms on my '86 (after towing it home...280 miles, I was moving). What concerns me is you said you have good fuel pressure even when stalling, but your relay and pump may be surging, which may register as good psi. Go to your local auto store and "borrow" a fuel pump relay test tool (i.e. new relay from a store with a good elec. return policy). As you know, it's located on the driver's side on the firewall. Good luck and keep us informed on your progress.

Da Mail Man

.....when my car started acting up like yours about a year or so ago, i would get only a maf code and so, replaced all the relays.

....however, i never got any other codes. the car would seem ok and then out of nowhere, die on me. at times it would die accelerating from a stop or even trying to start the car up initially. it even died on the interstate doing 80mph and i had to coast to a stop.

i went through checking fuel pressure, spark, coil, cap, rotor, ck'ed timing, all accessible electrical connections and couldn't locate the problem...and it was getting worse!

......tooling around in the helms manual, i stumbled on the "electronic spark control module" (believe that was what it was called) at the
p-side of the heater box and figured i'd try that.

......at the same time like i said before, i replaced the ignition controll module under the dist cap and that solved the problem. i wish i could be of more help but, can only relate to my experience.

Da Mail Man

.....as i said, it floored me when i took my fuel pump out to test it and i applied voltage to it. it barely ran!.....the readings on the rail were fluctuating and i was getting widely varying degrees of pressure readings.....i replaced the fp relay and even bypassed it through the aldl to eliminate that right away......during one test, it read normal...the next, it barely got to 20lbs......since i have replaced the pump, it runs like an animal running down the street with a fire cracker jammed up his behind!

kopbet89c4

I only wish I could get this car to run right. Anyways, the relay to the FP, the MAF, the MAF burn off and the main fan are exactly the same relay. I'll test it out first by swapping out the one for the main fan with the one for the FP relay.

But doesn't a bad FP relay set a code 54? We'll see, I hope my problem is solved for good if it turns out to be a bad relay...

Ahh. I just wanna pull out all my hair right now..... I don't want Christine to end up at a scrap yard and me in the morgue. Both of us are too young to die...

Da Mail Man

........yes, they are all the same relays.........go out and buy a "fresh one" for the fuel pump and be done with it.....as far as code for bad fp relay, i don't remember but, for roughly $10, eliminate that as a "probable" and save the old one (let's say it is fine) as an emergency spare..........you can bypass the relay altogether by applying 12vdc to a pin on the aldl.......

mikey whipreck

Did your ECM take a dump?

kopbet89c4

I will try that first thing in the morning without the car warming up. If it still stalls, then its gotta be a **** up ground or a wiring harness problem causing the ECM to freak out. I've been up all night trying to find something amiss with the wiring harness in the engine bay. Well, I have 4 spare ECMs that I tried and they all do the same thing. So it can't be the ECM. Maybe its about time to replace the wiring harness or go crazy. Then my stalling problem should vanish from the face of the earth...

I'm literally about to start throwing parts at my car... a little less gently than the dealerships here...

Da Mail Man

....whoa!, splash some cold water on your face!...don't be doing anything this drastic (wiring harness) that doesn't call for it!...i have spare ecm's also and subbed' mine also when i had my problem. if you have tried a couple of ecms then, assuming the chip isn't bad, then it is not the ecm.

.....i somehow don't think it is a ground problem either...ya know - a thought; a vacuum line just barely hanging on or with a split could do this also. you have stated that the car only (if i read it right) does this when the car is cold (below 150*?) and if that is correct, does not the ecm" take the place" of the majority of the sensors while in "open loop"?...mave you tried different chips or did you sub out different ecm's and use the same chip?....

CFI-EFI

Speaking of "deja vu". More fuel pump electrical system folklore. Once the engine is turning and has more than 4 psi of oil pressure, the fuel pump has two, parallel, sources of power. One is the fuel pump relay, and the other is the oil pressure switch. In order for an "intermitent faulty fuel pump relay" (never heard of such a thing) to affect the running of the fuel pump, the oil pressure switch would have to be bad. A simple test would be to unplug the fuel pump relay with the engine running. If the engine dies, the oil pressure switch is bad.

RACE ON!!!

Da Mail Man

....i have heard of crappy contacts in the relay but, that would make it just plain bad. i never heard of my fuel pump problem and i was surprised!..cfi, let me ask you a somewhat related question........if the relay was taken out of line, would the car start based on the oil switch and 4lbs?......should, shouldn't it?

kopbet89c4

Well, I hope you know I have only 4 vacuum lines to worry about. Brake booster, PCV, FPR, and the one for the HVAC. No more EVAP and EGR system. So that should eliminate the vacuum problem. As checked, all hoses are intact.