I have had this problem with my 97 Max. When I bought the car, I decided to do the timing chain and tensioner due to being extremely loud. Never test drove the car. Just cranked it, let it run and that was it. Car sat for a couple of months in the garage, then decided to do a 5sp swap. Finished that, took the car for a test drive and it began to stall. Similar to what a bad Maf does, but the only difference is that the problem will go away if either I accelerate lightly into each gear or slam on the accelerator. I figured the timing was off from when the chain was done, so I then decided to throw in another engine with less millage and that didn't fix the problem. Since then I have replaced Fuel pump, fuel filter, plugs, knock sensor, coils, ecu, Maf, have checked to see if I had any vacuum leaks and haven't found any. Checked for loose grounds and nothing. O2's were recently done. Only codes im currently getting are Evap solenoid and EGR flow, but those came up recently. I have constantly checked for loose connections, they are fine. The car doesn't need to be moving to notice or hear the stall. When in neutral if you accelerate little by little you hear it back fire through the exhaust. My questions are , if I was getting a misfire from one of the cylinders, wouldn't the ecu detected it. Things that I can think to check are the fuel injectors, but again wouldn't the ecu pick it up? What would be the best/efficient way to check that? I'm also thinking or re-grounding all the grounds off the coils and maybe the injectors. I know there are similar problems that are asked, but none of them appear to be like the one I have. It never stall at a same given point. I used to think that it was at a certain rpm, but it does it all through out depending on my driving. It does it no matter if the car is cold or warm, same difference. I need suggestions, ideas of any possible thing that might be causing it.

I want my 50 but check your coil packs man.

I take it you didn't read!!!

Somewhere along the way you mixed up some vacuum lines for the evap selenoid &/or egr. It sounds like Your egr or evap is opening when it shouldn't, causing an internal vacuum leak.

Just because you bought new coils doesnt mean that they work. Just saying. I had the same problem and replaced coils twice to fix it.

I find it very odd that you put another used motor in just because the old one was stalling?

WTF?

You have to do a bit of troubleshooting first my friend. Asking us here why you still have the same problem is like a big guessing game. Perhaps you should invest in a Chiltons repair manual. That book costs a lot less then your motor swap did.

Uhmmm, Im not looking for sarcasm, but I guess I didn't make my novel long enough to make it clear. First of all I did troubleshoot it. I had a bit of a complication with the timing chain. Second after consulting with some of the local guys, they also thought it would be the timing. Third the motor was given to me for free. I know these problems have been covered before. I just needed suggestion. I have searched but dont really find the exact same problem

The coils were tested by swapping from a functioning car, and still the same thing. Try again

^^What he said

O ok . I was stating my problem since he just said they were replaced and they were ok. Sorry man .

When I received my donor motor, it came from a daily user and none of the vacuum lines were touched. Motor was put in as a whole

Naw it's cool. I did come across an old thread were you stated you had that problem. I did try a few different sets just to be sure.

02 sensors swapped as well? Hummm, oh well than. I'm racking my brain here. hummmm. I can't really see a plugged exhaust causing those symptoms. If you dig deep in the depths of the fsm there is a procedure for doing a wiggle test on the harness IIRC. This is going to sound stupid but have you made sure your battery is proper, and your ecu connector is properly tightened?

Yeah o2's were replace about 2 months ago. I actually did both things. I have my ecu laying on the passenger floor, have checked to make sure it is well plugged. I will have to look into the "wiggle test" I do think that it might be a problem somewhere along the wiring harness, but not to sure if I should start going that route yet and if so where to start

When you swapped the engine - did you swap the IACV also?

The IACV was still on the donor motor. It was never touched.

Yeah, not to be "that guy" but have you checked your idle? Could be something that simple, that's easily overlooked, and easily fixed..... Check the Idle Air Control Valve or even adjust the idle screw...

I did this past weekend as well as cleaned the throttle. Idle came down a bit. It would start around 1K -1200RpM and gradually decrease, but then again we are having cold days so that doesn't help. It now starts somewhere around 800 - 1000RPM's

have you swapping ECU's just for laugh's sake?

Yeap! Tried 2 different ecu's already........

Well try adjusting the screw on top of the iacv.

besides the MAf that youve done have you looked into the catalytic converter?

Rear o2 would have picked up a bad cat, or I would of smelled it by now. Car is running with the same cat as when I purchased it and it was fine then. Problems started after work was done in the engine bay.

Other than what you mentioned, the only other thing that can very with RPM is the TPS. Did that second engine come with a TPS and you are using it now?

Does it behave the same with the A/C on or off?

As for the injectors, one easy method is to check the resistance of each injector to see if any particular injector is very different from the other 5.

i wouldnt rely on the rear o2 to pick that up, and the smell isnt always a side affect of a clogged catalytic converter....considering that youve ran through engines sensors and god knows what else you mine as well eliminate this from the line up IMO hell unbolt the exaust and see what happens

check to see if the egr valve is opening during throttle.. iv seen that problem before

I had also seen that EGR problem on other cars. But on our 4G, when the EGR doesn't open, the O2 sensor would detect a too rich condition, ECM would reduce gas, no?

If you experience stalling issues (with no CEL) and have tried all the basic troubleshooting like: clean TB, IACV, ECTS, plugs, fliters, coils etc and nothing seemed to help, you need to check your MAF sensor ground.

Simply back probe the black wire on MAF connector with positive lead of the voltmeter and negative lead pressed to one of the ground connections on the engine block.

The voltage at idle should be less than 9mv (0.009v), if it is above the value the sensor should be regrounded.

-I have checked to make sure that EGR valve is opening at throttle. It seems fine.
-A/C doesn't change anything.
-I will check resistance on the injectors, but didn't want to rely to much on that.(What is is suppose to read around?)
-Maf ground was the one thing I overlooked and completely forgot to check. I will try that tonight.

Recalibrate the TPS, redo the base idle, and run the car with the maf connected and disconnected

Clean the crank and cam sensors as well.

-Re grounded MAF, made no difference
-Ran car without Maf plugged and it stalled just like it should
-Re calibrated TPS, idle after warm up is around 600-700 RPM(still have me mess with it. I just wanted to see if it would make a slight difference when driving, but it didn't)
-Didn't get a chance to clean crank and cam sensors(was cold last night)

Any other ideas????

Also change the fuel filter and check the FPR

Fuel filter was just changed. FRP came from the donor engine and car ran fine. I'm getting the same problem with two different engines......... Without any CEL's im really having a hard time pin pointing what to change or where to look anymore.

Can I ask a stupid question.............. The only other thing that was shared between the two engines was a UDP. I know the there is a timing ring on it. Would someone enlighten me. Would that have anything to do with it?

The UDP could be causing the crank sensor to read wrong thus ecu tripping thus stalling

Would anyone have a pic of what the actual ring looks like? I can't remember out the top of my head what it looks like / integrated into the pulley or separate. The thing I don't get is wouldn't that trip a code for the crank sensor?

Its worth a shot putting on the stock pulley.

At this point I think I am going to give that a shot. I thought I was over thinking the situation, but wasn't sure if I was being rational.

Thanks Kev!

If anyone else might have had a similar problem with a pulley, feel free to share. I couldn't find anything similar.

I had the stock Ypipe and/ or stock cat clog up on me before and the car would not go over 5 mph. EXTREME BOGGING, like no other. <----That was with having the accelerator depressed all the way also. You mentioned something about exhaust, but I'm just throwing it out there. I thought the tranny gave out, thankfully it was not. Quite a wierd situation that was.....

Did it throw any codes? How did you find out it was the cat?