Bad injector driver in PCM

Shannon Neal

New Member
Joined
Jul 31, 2017
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9
Location
Dresden, TN, United States
I've got a 97 Tj 2.5l. I just swapped out my injectors to some 19lb four holes. Got everything installed, fired up and ran amazingly smooth. Went down the road and noticed after about a 1/4 throttle the jeep kind of fell on it's face. Seemed awfully sluggish. Would clear up and gain power as I eased off accelerator. The only time it would power up was at WOT. Shortly after, it started missing badly. I unplugged each injector and #2 didn't make a difference in being plugged in or not. I got it home and tested each injector with a volt meter. #2 tested like 1.4ohms with the others being around 14.5ohms. No big deal. Swapped another injector in that tested fine. No change. I can unplug my #1 wiring and plug it to #2 injector and the cylinder begins to work. So, the injector in it now is fine and I know I'm getting spark to that cylinder also. When I test the volts I'm getting around 13.5v across all injectors. I have also checked the plug itself and the actual wiring behind it, both were fine. I'm at a loss as to where to look now!? Is it normal for if an injector was to short out within itself for it to fry the pcm driver? Any help is much appreciated!
 
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Upon further testing turns out the injector driver for cylinder 2 has shorted out. Checked with a noid light at the injector i'm just getting a dim solid light instead of a pulsing one. Checked the wire for grounding and it isn't which is good. Pulled the pcm and opened it up and sure enough there is a burnt spot on the circuit board. Got a reman unit from flagship one sent and on the way for $300. Gonna attempt to fix my original pcm also.
 
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Just for the record as well, 4-hole injectors do absolutely nothing on these engines. Anything you think you feel is a placebo. This is a myth that somehow got perpetuated over a decade ago and refuses to die.

They won't hurt anything, but to set the record straight on anyone who stumbles upon this thread, they will do nothing whatsoever in terms of performance.

@Wranglerfix is the go to guy for PCMs, FS1 is a joke. He may be able to help you in regards to the PCM.
 
@Shannon Neal

Do you have the part number for your ecm? I believe the part ends in 355 or 652AE.

We can attempt to repair your current ecm as well.

You can call me at 866-888-7710 to discuss in further detail.

Thanks,

Mark
 
Did your new PCM fix the problem? I am having the same problem with mine.
Yes, it did! I went with ecuexchange off of ebay. You send them your pcm and they'll tell you if they can fix it or not. If not, you're only out like 15$ for shipping. I send it and got it back within a week and a half. Very pleased. Only cost like 125$ also. I got my actual pcm back too. They fixed it, resealed it, repainted, and sent it back ready to install.
 
Also, just to update the thread. DO NOT DEAL WITH FLAGSH*T 1. I fought with these idiots for over a month before finally receiving a pcm that was flashed for a cherokee :cautious: they sent me a pcm that had vtss (vehicle theft security system) programmed into it. Which meant my tj would crank and run for about 3 to 7 seconds before shutting off again. Contacted them and they wanted to act like it was my fault. After a little cussing and sending it back to them, my pcm sat idle for 3 weeks. Finally, I told them to keep it and just return my money. Which they finally did. Don't do business with flagship one. Everyone pointed me to wranglerfix and I should have listened, I just didn't have the cash to throw at it at the time.
 
glad it got fixed! I’m curious if mine is bad. Mine very intermittently misses and always starts on cylinder 1 and then moves to cylinder 2. I’m about 1 month into diagnosis and can littler pull the fuel injector wiring while it’s acting up and tell it’s not getting. I’ve ruled out spark and fuel pressure problems.

That injector has a steady 13v and the ground pulses but I’m wondering in the pulsing ground is low or not full. I just get the vibe this is a PCM problem. You said you actually opened your PCM and was able to tell your injector drive was bad?
 
glad it got fixed! I’m curious if mine is bad. Mine very intermittently misses and always starts on cylinder 1 and then moves to cylinder 2. I’m about 1 month into diagnosis and can littler pull the fuel injector wiring while it’s acting up and tell it’s not getting. I’ve ruled out spark and fuel pressure problems.

That injector has a steady 13v and the ground pulses but I’m wondering in the pulsing ground is low or not full. I just get the vibe this is a PCM problem. You said you actually opened your PCM and was able to tell your injector drive was bad?
Hook a noid light up to the injector that is giving an issue. A 12v led light is what I used to see how my injector was pulsing. Hook it up to an injector that is firing properly and then to the faulty injector so you know what it's supposed to do.

Yes, I was to the point where I was certain my pcm was actually bad. So, I actually removed my pcm and pulled the screws from it. It folds like a book. I opened it up and could physically see a burnt spot on my circuit board. Just note, if you eventually decided to do this you are opening up an extremely fragile unit. Be very very careful not to stick anything in to far when prying it open so you don't smash the circuit board or any components.

Also, you stated that the issue starts on 1 and then moves to 2. Have you ruled out that spark is firing properly and not phasing out in the least?
 
Yes, I was to the point where I was certain my pcm was actually bad. So, I actually removed my pcm and pulled the screws from it. It folds like a book. I opened it up and could physically see a burnt spot on my circuit board. Just note, if you eventually decided to do this you are opening up an extremely fragile unit. Be very very careful not to stick anything in to far when prying it open so you don't smash the circuit board or any components.

Also, you stated that the issue starts on 1 and then moves to 2. Have you ruled out that spark is firing properly and not phasing out in the le
I just ordered a noid light kit. My test light is a little vague so I will definitely be ruling that out.

As far as ruling out spark issue I guess as far as I got is that I’m getting spark to the cylinders but haven’t went as far as to make sure it’s correct with timing.
 
I had a similar issue so I thought I'd share.. I haven't had this TJ long but recently made the drive from FL to VA over a couple of days with pretty much no issue.
After a couple weeks up here the P0203 posted. I jumped to conclusions after reading through all kinds of posts and ended up replacing the injector. That fixed it (that's what I thought had fixed it...) until a week later when it returned, this time with an accompanying P0303. Again I scoured the internet and thought I'd overheated this injector (it was aftermarket) and so I ordered another plus some heat shielding.

I just replaced all that today to no avail, the P0303 cleared but the P0203 still posted....

Then I started considering the PCM, so I took a look. The plugs/pins all looked fine but I did notice my middle plug had a broken retaining clip.

When I seated it a little better an fired it up the CEL was gone and the rough idle/lack of power was gone.

I kind of figured more issues would've arisen from an unseated PCM plug but so far this worked for me.... Just got back from a couple hour cruise and it performed just fine.
See below for the zip tie method....
IMG_8022.jpg