Low Speed Running

[simonsparrow]

This has always been a problem on my '97 4.2 with a lot of stuttering around 1.5-2.5k revs. I've tried several things to fix it, such as Magnecor leads and an updated ECU chip from APM. They have all helped, but not made the difference I wanted.

I was figuring re-mapping was my only option....

I've just had the car serviced and had new throttle pots fitted and set up by Andy at APM. My theory was that for most of their lives, the pots will have been moving through a narrow angle repeatably (town driving/warmup speeds) and could be worn in this area, so it might be worth trying new ones. Besides, if I was going for a re-map, its good to know theat the car is in good shape anyway.

Well, the new pots have definitely made a positive difference. There is still a slight stutter at times (lets call it 'character' ) but on the whole is much smoother.

Could be worth a try if you've got the same problem.

[david smith]

interesting ... mine does the (so Im led to believe) 2k revs stutter ... ie 30- 40 mph round town

how much is a set of pots fitted ??

What milage u up to now?

DAS

[simonsparrow]

david smith said:

interesting ... mine does the (so Im led to believe) 2k revs stutter ... ie 30- 40 mph round town how much is a set of pots fitted ?? What milage u up to now? DAS

The pots were about £30 each from TVR power. Apparently the 4.2 and 4.5 ones are different and of course they sent me 4.5 ones. Luckily Andy had some 4.2 ones in stock and so just swapped them. Fitting was bundled in with the normal service, so couldn't say how much, but shouldn't be too long.

106,000 miles.

[redleicester]

I had the pots changed on my 4.2 a while ago, plus a new set of Magnecors, and whilst the rough running is better, it still isn't great..... would love to know if a remap would sort it!

[crazycats]

A lot of the light throttle "hesitation" with the 4.2 comes from the way the throttle linkage is designed.

The ball joints wear over time, and that small amount of play WILL have an effect.

I replaced the ball and socket joints on mine last year and it made a massive difference.

HTH

[simonsparrow]

crazycats said:

A lot of the light throttle "hesitation" with the 4.2 comes from the way the throttle linkage is designed. The ball joints wear over time, and that small amount of play WILL have an effect. I replaced the ball and socket joints on mine last year and it made a massive difference. HTH

I also did mine, and it also helped. I guess these things all need to be done in combination to get a good effect.

[redleicester]

Is that a big job?

[crazycats]

redleicester said:

Is that a big job?

Very easy, about 10 minutes to change the joints,

However the more tricky part cames in setting up the linkage for balanced airflows.

[gazzab]

I think joolz has an additional trade secret fix to keep them even better balanced?

[DuncanM]

I paid £35 for 2 throttle pots from TVR Silverstone .

If you're brave you can replace them yourself if you have the software to set them up.

About an hour tops for a garage to setup I'd have thought?

Duncan

[Steve_T]

simonsparrow said:

This has always been a problem on my '97 4.2 with a lot of stuttering around 1.5-2.5k revs....

Lambda sensors?