Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: Shaunfella on February 15, 2015, 07:40:20 AM

Title: TJ lack if power
Post by: Shaunfella on February 15, 2015, 07:40:20 AM
Hi folks...been a while since I've had any issues to post and ask for the forums invaluable help!

Got a 2006 TJ 4.0L sport.
 
The problem was that the car was very slow and had no pick up. It's usually fairly nippy off the mark but now just dies when I put my foot to the floor. There is a sort if low dull noise that sounds like air intake or something but it definitely does not sound right. I struggle to get 100 kph out if the cat whereas before it could sit at 140 no problem. When I put my foot down the revs go up but the speed doesn't

The engine light and code indicated that the O2 sensors were gone so had them replaced thinking that may have been the problem but no luck.

As u can tell I'm completely useless when it comes to under the bonnet stuff so would.apprwciate any suggestions for stuff to check before getting my pants pulled down at a garage. Spark plugs and O2 sensors cost me 350 and after checking online I think this was expensive.

Any help much appreciated!!
Title: Re: TJ lack if power
Post by: JamesH on February 15, 2015, 08:04:17 AM
You could check the fuel pressure, if the pump is failing it won't delivery enough fuel and can trigger error codes from the O2 sensors because the fuel air mix ends up wrong. There is a test valve on the fuel rail.
Title: Re: TJ lack if power
Post by: Mike Pavelin on February 15, 2015, 09:17:43 AM
I would check for a blockage in the cat / exhaust system.
Title: Re: TJ lack if power
Post by: Ezz on February 15, 2015, 01:17:28 PM
"The revs go up but the speed doesn't"

Clutch slipping..
Title: Re: TJ lack if power
Post by: Shaunfella on February 15, 2015, 02:04:05 PM
Thanks for the suggestions guys!
Title: Re: TJ lack if power
Post by: Shaunfella on February 15, 2015, 04:25:21 PM
Could it be the TPS?  Seen some stuff online that describes similar symptoms....
Title: Re: TJ lack if power
Post by: bgbazz on February 15, 2015, 04:31:55 PM
"The revs go up but the speed doesn't"

Clutch slipping..


I'm sort of wondering the same...any strange smells when this happens?
Title: Re: TJ lack if power
Post by: Shaunfella on February 15, 2015, 04:37:46 PM
"The revs go up but the speed doesn't"

Clutch slipping..


I'm sort of wondering the same...any strange smells when this happens?
Nothing out if the ordinary. Like I said ..The only noticable difference is the power/speed and the low pitch noise its giving out...really frustrating.
Title: Re: TJ lack if power
Post by: bgbazz on February 15, 2015, 05:17:07 PM
That's fair enough...the fact that the revs go up, but the speed doesn't, points to something slipping.
Title: Re: TJ lack if power
Post by: Shaunfella on February 15, 2015, 06:13:39 PM
That's fair enough...the fact that the revs go up, but the speed doesn't, points to something slipping.
It does accelerate but it's no were near as powerful as it was before the problem developed. The car would wheel spin no problem from a standing start....now it wouldn't pull skin off cold custard......
Title: Re: TJ lack if power
Post by: Shaunfella on February 16, 2015, 01:09:01 PM
Just out in the car again.....Top speed was 100 kph and the car wouldn't go above that or 3000 rpm....very very sluggish and sounds like it has a sore throat
Title: Re: TJ lack if power
Post by: wildwood on February 16, 2015, 01:23:08 PM
blocked cat or exhaust box......

Had this on a TJ after a mullaring  in the mud at Tong

Bits of aero bar cat had come loose and were blocking proceedings :jpshakehead:
Title: Re: TJ lack if power
Post by: Shaunfella on February 16, 2015, 01:52:06 PM
blocked cat or exhaust box......

Had this on a TJ after a mullaring  in the mud at Tong

Bits of aero bar cat had come loose and were blocking proceedings :jpshakehead:
You sound certain...that's good enough for me...take it that's why my O2 sensors were flagging up as gubbed then....
Title: Re: TJ lack if power
Post by: wildwood on February 16, 2015, 02:02:11 PM
District lack of power on road to beer purchase ......but had been OK on road to Tong....

Rattle cat was part of Prob but after taking exhaust box off...... Easy as was side exit shorty at the time .....we found it had taken a smack and although not visible from outside ....looking in to box the outlet was less than half the size.......

Driver ended up going home on cat and open pipe :icon_twisted:

Black TJ now owned by Cockney Boy.......but then multiple abuse sessions from the appropriately named 'Coyote Ugly' Chris........
Oh happy days indeed........ How we laughed at his demolition skills :hysterical:
Title: Re: TJ lack if power
Post by: JamesH on February 16, 2015, 05:36:43 PM
I had same symptoms, gutted the cat and got no change in the problem. Turned out to be a fuel pump only capable of delivering 20psi when the engine needs 49psi.
Title: Re: TJ lack if power
Post by: Shaunfella on February 16, 2015, 05:53:06 PM
I had same symptoms, gutted the cat and got no change in the problem. Turned out to be a fuel pump only capable of delivering 20psi when the engine needs 49psi.
Anyway to check the fuel pump without putting it into a garage??

And when I say check....I mean an easy method for the mechanically dumb....
Title: Re: TJ lack if power
Post by: Dave69 on February 16, 2015, 06:11:26 PM
screw a pressure gauge onto the fuel rail, should be a standard shraeder fitting (push bike inner tube type)
Title: Re: TJ lack if power
Post by: Yakko on February 16, 2015, 07:55:58 PM
I'm confused. Are the revs going up without the speed increasing?

If so, surely it can only be clutch?
Title: Re: TJ lack if power
Post by: Shaunfella on February 16, 2015, 08:23:32 PM
I'm confused. Are the revs going up without the speed increasing?

If so, surely it can only be clutch?
They're going up and the speed is too but it's got nowhere near the grunt it should have. Then once it gets to 100kph and 3000 rpm it won't go any further.  Usually it can sit at 130-140 comfortably.
Title: Re: TJ lack if power
Post by: JamesH on February 16, 2015, 08:29:54 PM
Fuel pressure test gauge screwed into test valve. Test gauge kit is about £40.
Title: Re: TJ lack if power
Post by: Shaunfella on February 17, 2015, 05:24:04 PM
It's going into garage tomorrow so fingers crossed it's nothing to painful (wallet wise).. hoping I can point him to the fuel pump  exhaust/ cat blockage and that's what it be!!
Title: Re: TJ lack if power
Post by: Brachunky on February 17, 2015, 08:27:24 PM
I'm confused. Are the revs going up without the speed increasing?

If so, surely it can only be clutch?
Put the tj's handbrake on firmly & try pull away in 2nd & see if the revs rise without moving forward :icon_winkle:
Title: Re: TJ lack if power
Post by: Dave69 on February 18, 2015, 06:33:33 AM

Not teaching people to suck eggs but identifying a slipping clutch is quite evident.

drive at 30 in top gear and then accelerate hard, car wont speed up that quick but the revs will raise quickly.

don't recommend the hand brake and drive away.
Title: Re: TJ lack if power
Post by: bgbazz on February 18, 2015, 06:45:06 AM
 :iagree:   ...with Dave. A slipping clutch will only be evident in top gear and low speed, just as he said. If it happens at low speed, in a low gear, it's totally knackered!
Title: Re: TJ lack if power
Post by: Shaunfella on February 20, 2015, 06:09:35 AM
It's an automatic I have........
Title: Re: TJ lack if power
Post by: Mike Pavelin on February 20, 2015, 08:58:09 AM
It's an automatic I have........

 :hysterical:

Does it change gear normally when you drive on a light throttle?
Title: Re: TJ lack if power
Post by: bgbazz on February 20, 2015, 04:01:05 PM
It's an automatic I have........


Knowing that at the beginning might have saved a few 'stabs in the dark'. :icon_rolleyes:
Title: Re: TJ lack if power
Post by: Ezz on February 21, 2015, 09:14:17 AM
It's an automatic I have........


Knowing that at the beginning might have saved a few 'stabs in the dark'. :icon_rolleyes:

Indeed  :banghead:
Title: Re: TJ lack if power
Post by: Shaunfella on February 21, 2015, 09:25:52 AM
Apologies!!
Title: Re: TJ lack if power
Post by: bgbazz on February 21, 2015, 05:33:33 PM
No probs...it just narrows down the possible options.  :icon_winkle:
Title: Re: TJ lack if power
Post by: Shaunfella on February 21, 2015, 06:40:18 PM
Going to take it to the garage this week at some point and have it sorted. O2 sensor codes flashing up again and they've just been replaced last week so I'm thinking the cat may be gone?? Assume this is costly to replace??
Title: Re: TJ lack if power
Post by: gazjeep on February 21, 2015, 07:06:59 PM
Cats aren't expensive, look on ebay.

Sometimes you can tell if its broken down if you get underneath & give it a bit of a thump with your fist, if you hear rattles from inside then its all broken up & needs replacing anyway  :icon_winkle:
Title: Re: TJ lack if power
Post by: Shaunfella on February 22, 2015, 10:18:35 AM
Cats aren't expensive, look on ebay.

Sometimes you can tell if its broken down if you get underneath & give it a bit of a thump with your fist, if you hear rattles from inside then its all broken up & needs replacing anyway  :icon_winkle:
I'll try this thanks....

Title: Re: TJ lack if power
Post by: Shaunfella on March 11, 2015, 10:08:34 AM
Just a wee update.  Hadn't got around to getting the TJ looked at...lack of power was still prominent but I was getting up and down to work at 100kph so decided to leave it. I'm off on holiday on Saturday so planned to drop it into the mechanic whilst away.

BUT..yesterday I was driving up Sheikh Zayed Road....car was struggling to get the usual 100kph and eventually wouldn't go above 80. After 15 mind the checks gauges light came on and the temperature shot up. I managed to get pulled over, and car recovered to mechanic.

He called there to tell me it's the muffler box that need replaced. Again, I've no idea about this stiff so does it sound plausible that a faulty muffler would have been causing these problems????

EDIT: been quoted around 150 quid for this repair. That's on top of the 380 he charged me last week to replace O2 sensors...
Title: Re: TJ lack if power
Post by: wildwood on March 11, 2015, 10:54:51 AM
I did mention this......reply no. 12.

Definitely plausible as I've seen it happen...... Hope this is end of your probs.... :icon_super:
Title: Re: TJ lack if power
Post by: Shaunfella on March 11, 2015, 11:09:07 AM
I did mention this......reply no. 12.

Definitely plausible as I've seen it happen...... Hope this is end of your probs.... :icon_super:
You did....Apologies!! Fingers crossed as it's doing my nut in now. I'm guessing had the mechanic checked this the other week I wouldn't have had to fork out for the new sensors!
Title: Re: TJ lack if power
Post by: Mike Pavelin on March 11, 2015, 10:40:36 PM
I did mention this......reply no. 12.

Definitely plausible as I've seen it happen...... Hope this is end of your probs.... :icon_super:

Ha! reply no.2.