Topic: mis-firing? cherokee (Read 7976 times)

BOP · « **on:** December 18, 2009, 06:35:08 AM »

Any ideas, when driving along at say 30-40mph foot steady on throttle pedal car starts to lurch back an forth and lose power like its dropped to only a couple of cylinders but if you boot ya foot down it'll pull no probs after a momentary delay, its only intermittatant but becoming more regular now! greggmo mentioned could be the tps playing up but I was thinking it might be coil? its got new leads an plugs in it so aint that! any ideas

scrw · « **Reply #1 on:** December 18, 2009, 07:52:27 AM »

I'd say tps. Try dropping it into a lower gear when it happens but keep the throttle in the same spot, does it keep misfiring? if so would point to the tps going bad

BOP · « **Reply #2 on:** December 18, 2009, 08:21:18 AM »

Quote from: scrw on December 18, 2009, 07:52:27 AM

I'd say tps. Try dropping it into a lower gear when it happens but keep the throttle in the same spot, does it keep misfiring? if so would point to the tps going bad

sorry should have put on its a 4L so its auto! its done it about 3 times in last couple months so it is intermittant which bugs the shit outta me! if it is the tps playing up does it just get to a point where it doesnt work at all or does it just keep playing up till ya replace it? dont want ta get stuck in the middle of nowhere! it also has a slight mis-fire on tickover which is what was making think about the coil?

BOP · « **Reply #3 on:** December 18, 2009, 10:13:26 AM »

I've now had a another theory added by reading up on another forum, someone described the same problem as I had and was advised its either the TPS or crank position sensor, as I dont know how or if I can check these parts short of replacing them I've ordered a plug in fault code finder/reader to see if the car will tell me which one or what is playing up!

Mike Pavelin · « **Reply #4 on:** December 18, 2009, 11:02:49 AM »

Upstream oxygen sensor.

BOP · « **Reply #5 on:** December 18, 2009, 11:20:06 AM »

Quote from: Mike Pavelin on December 18, 2009, 11:02:49 AM

Upstream oxygen sensor.

its a sensory overload at the moment! bloody electrical voodoo goin on in that there jeep! I hate electrics! thanks mike thats another angle of investigation to look at!

JamesH · « **Reply #6 on:** December 18, 2009, 01:10:07 PM »

Is this running on petrol (not LPG)?

A new upstream 02 sensor will ensure you're getting the best economy so isn't a bad thing to swap for new.

My 4.0 (on LPG) like to have new distributor cap, rotor arm and leads every 12-18 months and they're all fairly cheap to replace too.

I'v never had throttle position or crank position sensor issues but they are fairly common on 4.0s it seems.

BOP · « **Reply #7 on:** December 18, 2009, 01:42:45 PM »

Quote from: JamesH on December 18, 2009, 01:10:07 PM

Is this running on petrol (not LPG)?

A new upstream 02 sensor will ensure you're getting the best economy so isn't a bad thing to swap for new.

My 4.0 (on LPG) like to have new distributor cap, rotor arm and leads every 12-18 months and they're all fairly cheap to replace too.

I'v never had throttle position or crank position sensor issues but they are fairly common on 4.0s it seems.

running on petrol at moment (lpg planned for the new year!) I think i'll replace the 02 sensor's as a matter of course if its cheap enough to do! i believe it had a new distributer just before I bought it in october (gonna go check all the receipts I got with it now!) fitted new leads myself about a month ago, got a full set o plugs to fit as well now just to make sure! its proper playing up now just driven 5 miles home from work and it was kinda kangerooin nearly all the way home!

just read in haynes manual that models up to 1997 will display fault codes by flashing the check engine light off n on in relation to fault code (e.g. 2 flashes, delay, then 3 flashes equals fault code 23) after switching ignition on and off a couple of times. but mine (1998) needs the fault code reader tool! arse! wantin ta sort this out quick, broke up from work today and was plannin to do a couple of lanes over holiday, i've barely splashed it with mud since I've had it and thats just so wrong!

PtP · « **Reply #8 on:** December 18, 2009, 10:59:15 PM »

If you're near Stourbridge, then you're welcome to use my code reader!

BOP · « **Reply #9 on:** December 19, 2009, 10:37:32 AM »

Quote from: PtP on December 18, 2009, 10:59:15 PM

If you're near Stourbridge, then you're welcome to use my code reader!

Thanks Peter thats an offer I may well take you up on! gonna give it a coupla days see if the code reader I ordered yesterday turns up, I'm not too far away from you probably about half hour-hour away!

neilhull · « **Reply #10 on:** December 19, 2009, 09:13:03 PM »

HI my cherokee did the same . IT was the upstream 02 sensor . got a new one off the net i think it was £45 delivered

BOP · « **Reply #11 on:** December 20, 2009, 10:48:26 AM »

Quote from: neilhull on December 19, 2009, 09:13:03 PM

HI my cherokee did the same . IT was the upstream 02 sensor . got a new one off the net i think it was £45 delivered

Doh

ordered tps yesterday! oh well ho hum!

greggmo · « **Reply #12 on:** December 20, 2009, 07:04:35 PM »

just change em both anyway dood.

BOP · « **Reply #13 on:** December 21, 2009, 10:24:23 AM »

Quote from: greggmo on December 20, 2009, 07:04:35 PM

just change em both anyway dood.

I reckon thats wise

gonna do TPS before crimbo then do oxygen sensor come january pay day! read somewhere else that ya can dis-connect the upstream o2 sensor if it really knackers up, anyone heard of this before? bit dubious myself about this as wont it tit up what the ecu's doin?

BOP · « **Reply #14 on:** December 21, 2009, 02:12:53 PM »

This gets worse, went out to it this morning and it started then died straight away, repeatedly!

just had the men in orange jackets out to see whats occurin and i've got two fault codes, P1698 and P1694, one is a speedo error and the other is a pcm problem, basically all power is being cut to the injectors just after starting! I'm thinkin immobiliser maybe? anyone got any ideas before I get towed up to an auto electrician tommorrow and have my wallet emptied!

Panic mechanic! · « **Reply #15 on:** December 21, 2009, 03:58:25 PM »

change your lambda sensor as that will throw up pcm probs and will cause the engine all manner of probs.you can unplug it but the engine will run in limp home mode and use loadsa fuel

Mike Pavelin · « **Reply #16 on:** December 21, 2009, 06:33:11 PM »

P1694 and P1698 are both CCD bus communiction errors. Chances are a sensor has gone down and is disrupting the data flow between modules. Try unplugging the O2 sensors and see if it starts. If not, the next most likeley is the crank sensor, but it won't run with that unplugged.

BOP · « **Reply #17 on:** December 21, 2009, 07:39:11 PM »

Quote from: Mike Pavelin on December 21, 2009, 06:33:11 PM

P1694 and P1698 are both CCD bus communiction errors. Chances are a sensor has gone down and is disrupting the data flow between modules. Try unplugging the O2 sensors and see if it starts. If not, the next most likeley is the crank sensor, but it won't run with that unplugged.

Thanks Mike I'll try unplugging the 02 sensors tommorrow, I've unplugged the cps at the top connector by the fuel rail and replugged it with no luck, strange thing is the fuel gauge and volt meter for the battery are'nt registering anything either! I read on jeep forum earlier of someone having the same problem and it was the cps they also said that if you dis-connect the cps the gauges should read again, mine didnt!

bugger!

Panic mechanic! · « **Reply #18 on:** December 21, 2009, 08:54:33 PM »

If things are tight and you need to use the jeep, you can use one of the 02 sensors off the engine I have sitting here in the trailer to keep you mobile.

BOP · « **Reply #19 on:** December 21, 2009, 09:01:05 PM »

Quote from: Panic mechanic! on December 21, 2009, 08:54:33 PM

If things are tight and you need to use the jeep, you can use one of the 02 sensors off the engine I have sitting here in the trailer to keep you mobile.

Cheers panic your a gent! I'll try disconnecting the 02's tommorrow an if its them thats playing up I'll pm ya an sort summat out!

Mike Pavelin · « **Reply #20 on:** December 21, 2009, 11:07:43 PM »

The gauges won't work if the bus is down.

BOP · « **Reply #21 on:** December 23, 2009, 03:59:34 PM »

I'm now into the territory of giving it a damn good birching, disconnected the negative off the battery today to try n reset the fault codes, now the immobiliser has kicked in an I cant seem to re-set it to try starting it, does anybody know how to re-set it? I've tried the ignition on and hold down the unlock button, this removes the immobiliser light but as soon as I try and turn it over the security light comes on again! AAAGGGGHHHH

Mike Pavelin · « **Reply #22 on:** December 23, 2009, 05:45:10 PM »

If you have a '98 you have SKIS so it's no good mucking about with the remote as it has nothing to do with the immobiliser. Unplug the crank sensor and see if the immobiliser comes off and allows you to crank.

BOP · « **Reply #23 on:** December 24, 2009, 12:02:45 PM »

Yippee! sort of, just got it running again,petrol gauge and volt meter are giving me readings but oil pressure meter is not reading, volt meter is a mark or two below half way now probably due to the last couple of days of trying to start it, it ran for a minute or so then I switched it off and now it just cranks but wont fire up! bugger! might need to charge battery now maybe it doesnt have enough to fire it? I'm now also under the impression that mines a 97 model registered in 98 as it has a normal black key not a grey SKIS key?

Bubba · « **Reply #24 on:** December 24, 2009, 12:16:44 PM »

mmm bop you seem to be getting there

Author Topic: mis-firing? cherokee (Read 7976 times)

BOP

scrw

BOP

BOP

Mike Pavelin

BOP

BOP

BOP

neilhull

BOP

BOP

BOP

Panic mechanic!

Mike Pavelin

BOP

Panic mechanic!

BOP

Mike Pavelin

BOP

Mike Pavelin

BOP