Third drive and first Problem....engine 'hunting' at idle...
Third drive and first Problem....engine 'hunting' at idle...
Author
Discussion

Robertjp

Original Poster:

2,281 posts

254 months

Sunday 3rd May 2009
quotequote all
Car has been fine, done around 300 miles no trouble, but third drive yesterday eve, first sign of trouble.

First of all, i get a diagnostic code 'L'...which maybe i can put down to a common TVR thing, i have read this code if fairly common!!

But, came back to it after a meal out, obviously it was cold etc, but engine started to 'hunt' idle, revs would rise from 700 to around 1200 without any throttle input, and with gentle throttle, felt rough, as if it was missing....

Any suggestions?

The car was from a dealer but its a three hour drive back there, so wont be something i do in a hurry, but hoping i can sort something out with them...


shep1001

4,620 posts

218 months

Sunday 3rd May 2009
quotequote all
Robertjp said:
Car has been fine, done around 300 miles no trouble, but third drive yesterday eve, first sign of trouble.

First of all, i get a diagnostic code 'L'...which maybe i can put down to a common TVR thing, i have read this code if fairly common!!

But, came back to it after a meal out, obviously it was cold etc, but engine started to 'hunt' idle, revs would rise from 700 to around 1200 without any throttle input, and with gentle throttle, felt rough, as if it was missing....

Any suggestions?

The car was from a dealer but its a three hour drive back there, so wont be something i do in a hurry, but hoping i can sort something out with them...
I had a hot start problem with the Tam. when starting from 'hot' the revs would climb and hold to 1200rpm ish. small blip on the throttle or drive 100m or so and it would return to 850-900rpm. Crank sensor was replaced about £80 inc fitting and set up (if they are dirty they also play up so cleaning it might fix problem) and problem went away. not lumpy when I added throttle but there might be two problems to deal with here?

Robertjp

Original Poster:

2,281 posts

254 months

Sunday 3rd May 2009
quotequote all
OK, small update, replaced the battery today, seems to have cured all ailments, although im not sure how thats possible?

The old was was knackered, could hardly turn the engine even after 12 hours on optimate.

Car wasnt totally cold when starting up again after battery change, so maybe it only 'hunt' on revs from totally cold.

Misfire appears to be gone, im baffled, but the test drive just was cloud9 sweet as a nut...

Whitey

2,508 posts

313 months

Sunday 3rd May 2009
quotequote all
if the battery was knackered, then when you started it, it would just have enough juice to start the engine but the ECU would have lost power for a moment so it's gets confused until it has enough juice again when the alternator is charging things up. Hence the rough running, low rpm for a few minutes.

Jim Green

449 posts

238 months

Sunday 3rd May 2009
quotequote all
YEP - Low voltage to the ECU will cause idling problems.

UpTheIron

4,058 posts

297 months

Sunday 3rd May 2009
quotequote all
Jim Green said:
YEP - Low voltage to the ECU will cause idling problems.
And that is a massive understatement. I ran my Tuscan for over a year with a dodgy battery, including having to get a jump start after leaving the lights on - she wouldn't idle for 20 minutes or so, but once charged over a good thrash all was well again.

Robertjp

Original Poster:

2,281 posts

254 months

Sunday 3rd May 2009
quotequote all
Had the car just over a week and absolutely 100% love it, just on the learning curve though, and this was an early lesson!!

Just hope its sorted now!!

(and the dealer refunds my battery as promised wink )