Topic: 97 tj 2.5 cranks but no fire

[andrew383]

                 

found a broke wire 

i still have an idle/miss issue.We check with the scanner to see if any of the cyl were missfiring but none of them were and i have no code's.
It happens while driving as well.when i unplug the IAC it still surges.

[BarneyJeep]

you're not still running that SD coil are you?

put the stock coild back on and regap the plugs to 0.035 and see if its still there

[neale_rs]

Glad to hear you got it running again.

[sharpxmen]

                 

found a broke wire 

i still have an idle/miss issue.We check with the scanner to see if any of the cyl were missfiring but none of them were and i have no code's.
It happens while driving as well.when i unplug the IAC it still surges.

so was the wire going to the ASD? where was it broken? glad to hear you got that part sorted out. Now you just have to solve the misfire, i'm sure you'll figure it out soon.

[andrew383]

ive swapped coils.wires,plugs,cam/crank sensors. im out of ideas now.When we scanned it all cyl's were firing.Whatelse could it be?

[sharpxmen]

when you put the scanner on it - was it one that showed the cam and crank waveforms? also, were you monitoring the fuel pressure? You said that no cyls were misfiring - if that is indeed the case then it would lead to a fuel delivery issue, whether is from sensors (MAP, TPS) or the fuel system itself (fuel pump, regulator, injectors or injector wiring maybe) - can you determine if it is on one of the cylinders or not? (try to take one wire off at the time and see if there are no changes when you rev it then it could be the injector on that cyl) - you might want to also visually check the plugs and see if one is not looking healty.

[andrew383]

ill get it back on the scanner tommorrow,but im not sure it can the read the wave's between the cam and crank.
Ill also run it by the dealer to check the FP again.

What i did do is disconnect each injector and it still had the miss.I disconnected 2 at a time and it still missed.When i unplug the IAC,either o2's,TPS,or MAP it still miss's,plugs were changed along with cap and rotor.

[sharpxmen]

ill get it back on the scanner tommorrow,but im not sure it can the read the wave's between the cam and crank.
Ill also run it by the dealer to check the FP again.

What i did do is disconnect each injector and it still had the miss.I disconnected 2 at a time and it still missed.When i unplug the IAC,either o2's,TPS,or MAP it still miss's,plugs were changed along with cap and rotor.

i was thinking more on the line of looking at the waveform and see if you get any misses in signal. you did it right unplugging the injectors, the only thing you don't cover in that case is if one of them leaks. I would also check the ignition advance (not that you can adjust it but to make sure it's correct) - not sure if you can do that with the scanner but a strobe light would do. check the output of the MAP and i did have a misfire like problem (it would idle rough and stumble when accelerating) and in that case it turned out to be the TPS. good luck, but at least you got it running.

also, i was asking where was the broken wire?

[BarneyJeep]

pull the injectors again, and make sure you didnt roll one of the o rings when you put them in....lil bit of dielectric grease on the o ring should help it slide in

[andrew383]

well while looking on the scanner the timing would jump around between 8* and 20*ish when it would miss.
Ive got a new TPS thats going in tommorrow hoping to solve the high idle problem.The way the tach drops every few miss's leds me to think its a crank.cam sensor??I dont have my hayne's in front of me but whats the test for the MAP?Ive searched around a bit but cant find a test procedure.

I can still beat on it pretty good without any problems and it runs fine aside from the miss,but the Exhaust has a weird smell to it.

The broke wire was a red wire going from the PDC to a (factory)splice in the harness next to the batt and i think came from the start/run circuit.

[andrew383]

pull the injectors again, and make sure you didnt roll one of the o rings when you put them in....lil bit of dielectric grease on the o ring should help it slide in

never had them out,waitin on you to look at that fuel rail in the attic 
i have moved the injectors some when trying to pull the wires off the tho

[sharpxmen]

well while looking on the scanner the timing would jump around between 8* and 20*ish when it would miss.

that could be the crank, but not sure. the map (this is from memory so don't take it as a sure thing) should be around 0.65 at idle and 4.65 when you have the contact on and engine not running, from there it should vary between those 2 as you accelerate, if you suddenly open the throttle full would go to max and when you decelerate would go below the min (more vacuum due to higher rpm and closed throttle). i guess you have no codes at this point - you might have another bad wire too. I can't remember if you changed your tb - if you did you should throw in the old one just for a test.

[BarneyJeep]

does the ECU only read the map during closed loop mode or no? I know his miss happens no matter what temp the motor is at, and also at all engine RPMs, and throttle positions.

[sharpxmen]

diff between open and closed loop is that in closed loop uses o2 sensor input to adjust afr. all the other inputs are used in both instances.

[andrew383]

well it seems to be  day to day with this thing now.I went to load it up on the trailer yesterday for aride at it didnt want to go.IT had ran fine all morning but it started to break up in higher rpm's 3K+ and would die.Putting fuelin the intake did little help.So i left it at home,came back tried to start and its a no go.We pull the jeep around the yard back to to the front and while we were pullin i tried to start it but still nothin.
One thing to note is while trying to pull start it (4lo,1st)the rpms came up to about 1000 and even tho it wasnt running it still had that miss in it as i could see it on the tach and also hear it.So that leads me to believe that its not fuel related.