Hey guys, what is the likelihood that an ECU of 191,000 miles could be malfunctioning? I have changed out the injectors, the coil packs are good and am considering changing out the Bosche plugs that are currently in there. Problem is that the same cylinder is misfiring again after changing out the injectors. Everything operated just fine initially, then after a few hours, it started to misfire again. So the few hundred dollar question is, could it be the ECU or plugs or both?

 

regardless how the car runs, pull the bosch plugs and put in NGK plugs (plat or copper.. don't matter as long as you change them at the right intervals)

it COULD be a bad ECU but first make sure that there is no corrosion on any of thsoe injector plugs (and the coilpack harness plugs, etc), and that all your grounds are making good clean contact, etc.

 

Do the plugs ASAP and hope they didn't damage you coils.

 

could be the power transistor unit

 

I intend to get some NGKs in as soon as possible!

Where would that be located and how would I test for that?

 

It's located right next to the cam position sensor and I'm not sure how to test it. If you have access to a spare power transistor unit, you could try swapping it out for yours. If your misfire problem goes away, then that's your problem.

 

don't know for certain on a VE, but i'd expect the PTU to affect ALL cylinders, ie, the car won't fire up at all (code 21). On the VG it's definitely the case, on the VE perhaps it isn't. See if your car will start at all with the PTU unplugged.. i don't think it will but i might be wrong.

 

A while ago, my ptu caused a intermittent single cylinder misfire. I replaced it and the misfire went away.

 

gotcha. i remember somebody making a thread about it back when i was a n00b on here before i could remember who was who.. i guess that was you. everyone was like "uh, you mean the coilpack?" and the OP was like "no.. it's this other thing, just one of them for all the cylinders".

 

I don't think I ever posted a thread about it.

 

o .. hm well someone did in like the spring of 2007. but if your PTU caused that issue, then that's certainly something to check. i know greeny has a good one on his now-parts motor.. not sure if he's selling parts off the motor, but he probably is. there is an FSM procedure to test it tho. http://boredmder.com/FSM/Nissan/Maxima/1994/ec.pdf page 262 (EC-264)

 

Now that I think of it, you should test the misfiring cylinder for spark when the cylinder is misfiring. If you have spark, then it's the injector, injector harness, or ecu that's causing the misfire. If you don't have spark, then it's the coil, coil harness, power transistor unit, or ecu that's causing the misfire. FYI, it's highly unlikely that the ecu is bad. Good luck!

 

I thought there was a procedure to test the PTU, but I wasn't sure.

 

neither was I... i didn't actually bother to read through the procedure the first time i just saw "power transistor" and posted the link. so what i first posted, that's how to test the entire system, like if you got a code 21... but the actual electrical test procedure for just the PTU is on the top of pg EC-326 (pg 324 on the .pdf)

 

with PTU OR CPS unplugged VE will never start, will jus crank ....

and there is not many chances that ur ECU is bad but the ground signal wire from ECU...it could be PTU...test it and see if things r according to the FSM.....

how about ur spark plugs? did u change them too?....i was having misfire at WOT but since i changed my all 6 spark plugs with NGKs...my misfiring is stopped....

 

From what I have found, I am missing the spark. There seems to be fuel, because that part was just tested before it was installed. My guess is that it is the plug, but funny how it happens to be the same cylinder and that it was fine initially when the injectors went in. Everything was firing, then it started to miss.

I have not changed out the plugs yet as I have yet to get my hands on some NGKs. Could I pick some platinum ones at a local NAPA store?

 

yes u can pick up from any local auto parts store....plus can u post the pic of the spark plug which is causing misfiring?......it might not be spark plug itself or its quality which is getting toasted again and again in the same cylinder....anyways, post the pic of plug and lets see....

 

as long as they are NGK you should be fine. You can run the copper just as easily as the OE installed laser platinums

 

Update on the situation. It is not the ECU (that was tested), it is not the coils, or the plugs (some NGK coppers were put in regardless). It is still misfiring. MAF was cleaned as well. The next theory is that there is a leak in the intake somewhere...any other suggestions?

 

take some propane in a small canister with a hose that you can wand around to help pinpoint the leak. when the propane gets near the leak the engine RPM will increase.

 

Did you ignore my posts??

 

Have you checked/changed the plug wires?

 

The VE30DE engine doesn't have plug wires, it's a coil on plug design..

 

My bad...

 

no prob.. where joo at in tenn.?

 

the spring can go bad along with the boot, I haven't seen it yet on a VE though. VERY common on ford 4.6s

 

 

No sir. At this point, the harnesses seemed to be clean.

 

i think he was talking about checking the PTU...

 

Are you absolutely SURE the coil packs are good??

 

I was under the impression that it would not start if that were malfunctioning from what folks have said so far on that so I have not checked that.

The cylinder that was giving me trouble seems have a good coil pack.

 

Read post #8

 

swap that coilpack around to different cylinders and see if the misfire follows the coil, or stays with that cylinder.

 

No dude...Don't ever install Bosch plugs in japanese vehicles nor F/I motors, those plugs miss like crazy in Japanese vehicle and show no signs of defects, they're just not for our vehicle your ecu is fine!

 

Most of the time, this is the case with the ptu.(a no start condition) but keep it in mind as a possible culprit..

seems to have one?? sorry dude but that is not much of a diagnoses.. Have you checked the front coils for cracks? Keep in mind, even if they are not cracked doesn't necessarily mean they are good.

Did you remove your injectors from the fuel rails when you replaced them?? or did you just swap in a used set of injectors still in the rail??

If you removed them, you might have pinched a o'ring when you installed the injector on the cylinder that is currently missing. If you just replaced the injectors with a used set of rails, then you may have a bad injector.


Obsession...do this...

 

Ah, whoops. I must have overlooked that one.

Coil packs have been moved around and they all seem to be working well.

I know, they were in there when I bought the car. Figured that they worked all right for the time being so I kept for a bit. So you are saying that despite the fact that the plugs might be clean and spark there is the potential that it might not anyway?

 

So has there been any change yet?
I dont think I have this same problem, but It might be similar, so to
know what works for you would be nice!

 

More than one person in this thread has said you need to use NGK plugs instead of Bosch. I'll be one more. Switch them and then come back if there is still a problem.

 

read post #19

 

this thread seems to be having that problem.... my bad