Topic: 97 TJ misfire (Read 5580 times)

Dodster · « **on:** September 27, 2011, 10:36:18 PM »

Guys i need some advice please..
Ive had a problem over the last 12 months or so where after winching and getting hot the engine sometimes misfires. It either goes after a short while or occasionally it conks altogether but will restart ok after a few minutes.
Today ive been to get fuel ready for the weekend, no problem on the way to the garage but afterwards on the way back when its warmed up I have a constant misfire, worse when in gear under load and sounds like more than one cylinder missing. On tick over it chugs but doesnt conk out altogether.
Ive started the engine and had a look in the dark but no sign of arcing anywhere, there are no fault codes and for some reason I suspect the coil..
Ive got limited time to fix this/get parts etc so I wondered if anyone has a better idea where to start first to save time.

Plugs/leads/cap/coil or upstream oxygen sensor or anything else.

Thanks
Phil

Nosebolt · « **Reply #1 on:** September 27, 2011, 10:53:34 PM »

are you running a split battery system? cos my first guess would be your loosing battery power, low voltage to ecu causing misfire till it recharges enough to compensate

Bishops Finger · « **Reply #2 on:** September 27, 2011, 11:24:18 PM »

Leads or maybe O2 sensor...given my nob all knowledge...

gazjeep · « **Reply #3 on:** September 27, 2011, 11:31:19 PM »

Phil, you going to Bodenham ?

Got a new dizzy cap, plugs & leads sat in the garage if you want to try them to discount the simple stuff ?

JamesH · « **Reply #4 on:** September 28, 2011, 11:30:55 AM »

Phil, mine's gone the same way and why I had to pull out of TT. I have fault codes for O2 sensor high voltage and cam position sensor though.

Through some forums searches, coil and new 02 sensor seem most likely, also checking wiring for any damage. I've had to hold off buying parts until pay day - if you make any progress let me know and I'll keep you updated on mine as well.

Dodster · « **Reply #5 on:** September 28, 2011, 05:02:08 PM »

Thanks for the replies..
I dont have a split charge system as yet NB but ive tried hooking another battery up in parallel to boost mine but no difference.
Gaz, thanks for the offer but Im not going to Bodenham Im supposed to be going to West Harptree although its getting more and more doubtful.

Anyway ive managed a couple of hours this afternoon... Its still misfiring straight from cold, chugging at tickover worse under load. Changed the coil cos I had one spare no difference. Checked the cap and rotor and appear good.
Pulled the leads one by one and its No5 (from front to back) thats missing if that means anything, changed the lead and plug still no difference but there is a spark at the plug..

So I disconnected the O2 sensor and it made no difference to the running whatsoever...does that mean its looking like the O2 is bost or is it the opposite?
Got codes 12 and 55 which I think are normal..still no other codes or check engine.

Any help, including prayers, gratefully and desperately received..

Edit...a bit more.. I swapped the elec connector to injector 5 with the one for injector 4, no difference and misfire is still at no 5, would this then point to the injector being the culprit..?

gazjeep · « **Reply #6 on:** September 28, 2011, 07:10:04 PM »

When are you going mate, I can take the bits to work in Redditch tomorow & head up your way after work or you can call in to ours, just off Jct 6 M5 & I can leave bits in porch for you on your way south if that helps.

More than welcome to compare yours to our 98

07519 585 933 if I can help at all Phil

Dodster · « **Reply #7 on:** September 28, 2011, 07:36:42 PM »

You're too kind Gaz..
Thanks again for the offer, I should be going on Friday pm but tbh Im not going to set out unless I know I can fix it, Im fairly sure its not plugs leads or cap and I wont have enough time before or when I'm there to fanny around with it.
Really appreciate the offer tho..

Panic mechanic! · « **Reply #8 on:** September 28, 2011, 07:52:45 PM »

where are you dodster? I am by j4 M5 and still have tanks obd scanner that can do real time scanning rather than just pulling them off on the display and more than welcome to take a look if you want.

willo · « **Reply #9 on:** September 28, 2011, 07:56:34 PM »

This is where a guest appearance from the doctor would be useful

Mike Pavelin · « **Reply #10 on:** September 28, 2011, 07:59:10 PM »

If it's stopping the engine, it may well have set a trouble code. Could be crank or cam sensor as well.

Dodster · « **Reply #11 on:** September 28, 2011, 08:24:04 PM »

Panic Im near lichfield so not too far but I cant drive the Jeep anywhere cos its missing too badly, I might be able to get my hands on a scanner though but if I cant I will get back to you if thats ok cos I could stick it on a trailer...cheers for the offer.

Mike, the engines not cutting out at all just misfiring..

Guess there are just too many possibilities without hooking up to a scanner or diagnostics thingy..

, I thought it was going to be a fairly easy fix like it was when the points went in my vauxhall viva,..

Thanks again for the replies.

Dave69 · « **Reply #12 on:** September 28, 2011, 08:31:48 PM »

you may have answered your own question.......

coil....no change
leads....no change
spark plug....no change
O2 sensor disconnect....no change
injector power lead swap....no change

without looking at a detailed scanner you would have thought the injector might be suspect.

depends on how easy they are to swap, so change the problematic No.5 for say No.2 and see if the misfire moves

Dodster · « **Reply #13 on:** September 29, 2011, 01:50:24 PM »

Thanks Dave,
I've given up on it being fixed in time now so will have a look at the injectors at the weekend..
Many thanks for all the help
Phil

Delk · « **Reply #14 on:** September 29, 2011, 03:28:28 PM »

Last year my 98 started to do something similar. After some time it would start to sputter and completely loose power. After I shut it down for a bit it would run fine again. It would repeat this at shorter and shorter intervals driving me nuts and getting worse. No trouble codes or lights. After checking item after items tucked a pressure under a wiper blade with a flex hose under the bonnet connected to the fuel injector manifold. It was done in the most professional manner with proper sticky tape. After twenty minutes of driving the gauge started to fluctuate and the pressure dropped right off followed by the sputtering and issues. Needless to say it was the fuel pump cutting in and out that caused all the problems.

Good luck

Bishops Finger · « **Reply #15 on:** September 29, 2011, 05:38:12 PM »

Phil from experience Delks idea is worth investigating

Dodster · « **Reply #16 on:** September 29, 2011, 06:19:04 PM »

Quote from: Bishops Finger on September 29, 2011, 05:38:12 PM

Phil from experience Delks idea is worth investigating

Yes thanks Delk, I'll put it on the list, If its not that or the injector then I will sort out putting the scanner on it and report back. If that doesnt work Ive got a box of matches somewhere.

Would just like to say thanks again for all the offers of help..

donk498 · « **Reply #17 on:** September 29, 2011, 06:38:51 PM »

If the injectors are the same between 94 xj and yours, i've got some spare. Only in walsall so not far from you.

Dave.

Bishops Finger · « **Reply #18 on:** September 30, 2011, 03:53:21 AM »

Phil..

When my fuel pump played up the TJ would misfire and stop running....Leave it to cool off and it would start but occaisionaly misfire...RAC escorted me home and took it to Westbury where they finally identified the issue as the fuel pump....man they were soooo happy at removing the fuel tank skid plate...later spoke to the late Mark Gasser about it as Westbury tampered with the throttle bodyspacer..thankfully no issue

He said not normlly a problem but ya can get upgraded pumps from the US...

Hope this further snippet helps..

Delk · « **Reply #19 on:** September 30, 2011, 07:56:50 AM »

I managed to match my fuel pump to a Honda or something along that lines since the pump is quite common. I ended up paying around 70 pounds. Merlin Motorsports has the direct pumps listed online for less then a 100 pounds.

http://www.merlinmotorsport.co.uk/FUEL-SYSTEMS-Fuel-Injection-Pumps-JEEP-Wrangler/c26_2686_2911_2914/index.html

Dodster · « **Reply #20 on:** October 09, 2011, 08:28:27 PM »

Cheers Donk for the offer but Ive ruled out the injector..
short update... am now looking at the upstream O2 sensor, Ive taken out and cleaned the one I have and there was a momentary improvement enough to make me think hmm maybe this is it so just waiting for a replacement and see what happens..

Author Topic: 97 TJ misfire (Read 5580 times)

Dodster

Nosebolt

Bishops Finger

Dodster

Dodster

Panic mechanic!

Mike Pavelin

Dodster

Dodster

Delk

Bishops Finger

Dodster

donk498

Bishops Finger

Delk

Dodster