Topic: Bad throttle position sensor? (Read 7452 times)

gordy · « **on:** March 24, 2013, 10:26:36 AM »

Looking for some advice fellas. 98 TJ 4.0l.

Symptoms:
When the engine is cold or warm (after a short journey for example) the jeep hesitates, put the throttle wide open there's very little power, in fact sometimes feels like its gonna stall, at the same time the jeep bucks (kangaroo petrol was a term used in the past!).

Idle engine speed drops down to 500 rpm, then goes back to normal. Its lacking so much power the only option is to pull over, give it a few revs in neutral and then it clears itself, and you are good to go, will then operate normally with no hesitation or bucking in any gears and have no problems on a 20 mile journey and at normal operation temp had no problems..............Until last night lol.

Jeep was at 100deg, got to a junction shifted into neutral the revs were at 1200, then suddenly drops to 500, then back upto 850, noticed a slight loss of power then cleared itself and back to normal.

The check engine light does not and has never come on when the jeep is doing any of the above.

So far i have removed and cleaned the throttle body, removed and cleaned the Idle air control valve (IAC), removed and cleaned the disributor cap and rotor, spark plugs will get renewed as soon as the 5/8 socket arrives, battery fully charged, checked the vacuum hoses, done the electrical wiggle test. I'm thinking this is a sensor issue. Extensive internet searches show this is a common problem with jeeps and could be one of many faulty sensors.

My symptoms are pointing toward a faulty throttle position sensor (TPS). IE erratic idle, surging rpm while driving, loss of power, bucking.

Advice appreciated, cheers.

gazjeep · « **Reply #1 on:** March 24, 2013, 10:31:01 AM »

Had similarly identical issues with our 98 TJ

Scanned it, came up with fault code for fueling issue.

Replaced, TPS & both oxygen sensors & double checked / cleaned / sqibbed electrical cleaner in electrical connection block by the fuel tank.

Problem went away instantly, dont know which of the above cured it but it has worked fine ever since.

Bought the parts from Rockauto, lots cheaper then over here & about 3 day delivery from USA to my door.

Good luck

gordy · « **Reply #2 on:** March 24, 2013, 10:44:51 AM »

Does the check engine light have to come on to thrown a code that can be picked up on the scanner?, did your CEL come on? makes sense to replace all those sensors at those low prices from Rockauto.

MOCAJ · « **Reply #3 on:** March 24, 2013, 10:48:49 AM »

The CEL was not on

gazjeep · « **Reply #4 on:** March 24, 2013, 11:07:08 AM »

Mocaj is spot on, no CEL light, but when he scanned with £15 reader it showed fault codes.

Replaced (well MOCAJ did) all leads, plugs, dizzy cap, rotor arm, ok for a few days then it stared all over again & went the sensors route

Cant receomend highly enough getting a scanner off amazon / ebay, will find a link

Here you go

http://www.amazon.co.uk/CAN-Bus-Trouble-Diagnose-Diagnostic-Scanner/dp/B001CBBY7O/ref=sr_1_2?ie=UTF8&qid=1364119650&sr=8-2

gordy · « **Reply #5 on:** March 24, 2013, 11:22:18 AM »

Cheers guys, the misses has an amazon account, i'll ask her to order one lol!

gordy · « **Reply #6 on:** March 28, 2013, 05:23:11 PM »

All 6 plugs were loose, removed and replaced, runs better. Undersized air cone air filter fitted. Will give it a proper road test when I can but seems sorted. BTW! I ran tests on the MAP sensor and the throttle position sensor, both appeared to be working within specifications so went the cheap route first.

gazjeep · « **Reply #7 on:** March 28, 2013, 08:07:52 PM »

Good result

gordy · « **Reply #8 on:** September 25, 2013, 08:58:25 AM »

Was not filter still happens occasionally.

gazjeep · « **Reply #9 on:** September 25, 2013, 03:23:14 PM »

Did you get a scanner ?

Sensors from rockauto my good chap is the way to go

gordy · « **Reply #10 on:** September 25, 2013, 03:57:32 PM »

I did, when it's doing it I plugged a D900 scanner in and the only fault I ever got was a one off variable speed sensor, it was reporting the vehicle was doing 768 kph!, I reset the fault and it never came back but I still have the original fault, I'm living with it, I have no problem with a 300 mile road trip but it pisses me off to wanting to solve it.

JamesH · « **Reply #11 on:** September 25, 2013, 10:17:41 PM »

I have TPS with 3 round pin connector you can have for the cost of postage - Wildwood kindly sent it to me but mine has the 3 flat pin connector type so it doesn't work for me.

bonza · « **Reply #12 on:** September 26, 2013, 01:56:40 AM »

when driving using cruise control my Heep was speeding up and down a few MPH and giving me the shits. ended up replacing the TPS and now all's good resulting in cruise behaving itself. previously no codes or anything and idle was fairly stable. think it may have been an early indication of TPS failure, plus bought it from rockauto and was delivered in no time

gordy · « **Reply #13 on:** September 26, 2013, 07:56:38 AM »

Quote from: JamesH on September 25, 2013, 10:17:41 PM

I have TPS with 3 round pin connector you can have for the cost of postage - Wildwood kindly sent it to me but mine has the 3 flat pin connector type so it doesn't work for me.

Thanks James thats great PM me your paypal email and cost and I'll fire over a payment, cheers.

gordy · « **Reply #14 on:** September 29, 2013, 01:25:53 PM »

So I have ordered a new O2 sensor upstream from Rock Auto. Live data on the scanner showed no voltage pulse at all from the sensor, it's reading more or less steady .5v at idle, it should pulse from 0.1 to 0.99v and under throttle voltage out too but did not throw an OBD code, borrowed a O2 sensor socket set and had a go at getting the old one out, bastard did not want to come out and those slotted sockets rounded off the nut, had to cut the sensor at the nut, got the BFH out and hammered the bastard, then hammer on a 21mm socket and with a long breaker bar it came out, but chewed the thread up l ol so re cut the m18 x 1.5 thread ready for the new one,
will report once fitted.

gazjeep · « **Reply #15 on:** September 29, 2013, 07:12:09 PM »

Fiddley things them sensors, hopefully your new ones come pronto

gordy · « **Reply #16 on:** September 29, 2013, 08:07:01 PM »

Get this, ordered it Friday at 17.30 UK time, it arrived via FedEx at Stansted airport at 21.35 yesterday and will be delivered Monday 30 sept before 12 midday, California to Memphis to Suffolk UK in what, 60 hours and that's at the weekend, that's unbelievable.

gazjeep · « **Reply #17 on:** September 29, 2013, 10:34:46 PM »

Ordered some parts last week while in florida, I fooked up the house number with the zip code.

Long story short, parts went from three different shipping points to Alaska & still made it to actual hotel address in Florida keys by lunchtime on the friday 2.1/2 days later.

So long as you can suck up the shipping costs for your purchase, I wouldn't bother going elsewhere stateside for standard parts

gordy · « **Reply #18 on:** September 30, 2013, 11:41:29 AM »

The sensor arrived this morning at 08.45, tightened up ok and problem sorted. Rock Autos and Fedex rock.

Ezz · « **Reply #19 on:** September 30, 2013, 12:17:28 PM »

Quote from: gordy on September 30, 2013, 11:41:29 AM

The sensor arrived this morning at 08.45, tightened up ok and problem sorted. Rock Autos and Fedex rock.

Result

Author Topic: Bad throttle position sensor? (Read 7452 times)

gordy

gordy

gordy

gordy

gordy

gordy

bonza

gordy

gordy

gordy

gordy