Cold start and unstable idle when hot?
Discussion
Morning All
Poor relation signing in from the Wedge world :-)
I've recently bought a 400se Wedge. Which many years ago had an early Griff 5.0L lump fitted by a TVR specialist. Assume it was an original engine failure and the upgrade seemed a good option at the time?
The car's been off the road for 3-4 years. Due to a back issue I got a friend to recommission the rear brakes and give it a general refresh to get it the the MOT. The car started and ran pretty well for the first couple of short trips out. But the idle never seemed to drop fast enough when changing down or coming to a stop with the clutch down. It would hang around 1500 to 2000rpm and then after around 10 seconds or so would drop to normal idle.
When driving for example in 4th at 30ish mph it would be like having cruise control, it would just drive along with no pedal input.
Fast forward to last weekend. The GB remote bushes had failed, so a friend came over to lend a hand and replace them for Poly bushes. Since then it's been almost undriveable from cold. I took it out on Sunday morning to get fuel ready for a blast out in the PM. The garage is 5-6 miles away. the car was stalling, dropping revs and generally all over the place. Stopped at the fuel station, thinking this is going to be a challenge to get home. Filled up and started the car. Back to 100% driving normally, not even the idle issue.
Got home and left ot for half an hour. Started no problem, running and driving great but idle issue is back.
I got the Rovergauge software and lead yesterday, but no really sure what I'm looking at. Any advice where to start would be appreciated.
Some of the guys on the forums have suggested looking for air leaks. I've ordered a smoke tester for the weekend, just to make sure. But surely it the was an air leak the symptoms wouldn't be intermittent?
TIA Karl.
Poor relation signing in from the Wedge world :-)
I've recently bought a 400se Wedge. Which many years ago had an early Griff 5.0L lump fitted by a TVR specialist. Assume it was an original engine failure and the upgrade seemed a good option at the time?
The car's been off the road for 3-4 years. Due to a back issue I got a friend to recommission the rear brakes and give it a general refresh to get it the the MOT. The car started and ran pretty well for the first couple of short trips out. But the idle never seemed to drop fast enough when changing down or coming to a stop with the clutch down. It would hang around 1500 to 2000rpm and then after around 10 seconds or so would drop to normal idle.
When driving for example in 4th at 30ish mph it would be like having cruise control, it would just drive along with no pedal input.
Fast forward to last weekend. The GB remote bushes had failed, so a friend came over to lend a hand and replace them for Poly bushes. Since then it's been almost undriveable from cold. I took it out on Sunday morning to get fuel ready for a blast out in the PM. The garage is 5-6 miles away. the car was stalling, dropping revs and generally all over the place. Stopped at the fuel station, thinking this is going to be a challenge to get home. Filled up and started the car. Back to 100% driving normally, not even the idle issue.
Got home and left ot for half an hour. Started no problem, running and driving great but idle issue is back.
I got the Rovergauge software and lead yesterday, but no really sure what I'm looking at. Any advice where to start would be appreciated.
Some of the guys on the forums have suggested looking for air leaks. I've ordered a smoke tester for the weekend, just to make sure. But surely it the was an air leak the symptoms wouldn't be intermittent?
TIA Karl.
Belle427 said:
The biggest problem for idle issues is the stepper motor, it needs to be removed and cleaned thoroughly.
There are loads of threads here on it.
Vacuum leaks are another common issue but id start with the above first.
A screenshot of Rovergauge with the car running may help.
I've swapped the stepper out for a new one which came with the car. However it looks like it could be an ebay special. So I'll have a look around for a better quality one.There are loads of threads here on it.
Vacuum leaks are another common issue but id start with the above first.
A screenshot of Rovergauge with the car running may help.
The throttle position never drops lower than 11% on the Rovergauge?
I can help with the Rover Gauge stuff. Just need you to run a logfile in specific way, will post that in a bit.
I fully agree with belle427 this does very much sound like a stepper or vacuum leak. I'd favour vac leak as temp seems important ie as the metal heats up it expands and leak either opens or closes a bit although stepper could also be doing the same.
I fully agree with belle427 this does very much sound like a stepper or vacuum leak. I'd favour vac leak as temp seems important ie as the metal heats up it expands and leak either opens or closes a bit although stepper could also be doing the same.
1. Plug the 14CUX cable into the loom connector on the car
2. Start RoverGauge software
3. Setup RG options settings as follows
a. COM - COMx (use whatever COM port works for you)
b. Speed - mph
c. Temperature – Celsius
d. Parameters to log – all but not road speed or gear selection
4. Set RoverGauge main screen as follows:
a. MAF – Direct
b. Throttle – Absolute
c. Trim – Short Term
5. Turn on the ignition switch and press ‘connect’ to link 14CUX with your laptop.
6. Preferably start the car from cold.
7. Start logging the data (Start Log F5) and drive the car for 15 minutes on a local roads (eg A or B class to get varying running conditions) then stop the car and allow the engine to idle for a further 5 to 10 minutes. (DO NOT TOUCH ANY OF THE CONTROLSAT THIS STAGE)
8. You can now stop logging data by pressing “Stop Log F7”
9. Send the logfiles (held in a sub folder where RoverGauge is) to me (I will msg you my email address)
2. Start RoverGauge software
3. Setup RG options settings as follows
a. COM - COMx (use whatever COM port works for you)
b. Speed - mph
c. Temperature – Celsius
d. Parameters to log – all but not road speed or gear selection
4. Set RoverGauge main screen as follows:
a. MAF – Direct
b. Throttle – Absolute
c. Trim – Short Term
5. Turn on the ignition switch and press ‘connect’ to link 14CUX with your laptop.
6. Preferably start the car from cold.
7. Start logging the data (Start Log F5) and drive the car for 15 minutes on a local roads (eg A or B class to get varying running conditions) then stop the car and allow the engine to idle for a further 5 to 10 minutes. (DO NOT TOUCH ANY OF THE CONTROLSAT THIS STAGE)
8. You can now stop logging data by pressing “Stop Log F7”
9. Send the logfiles (held in a sub folder where RoverGauge is) to me (I will msg you my email address)
blaze_away said:
1. Plug the 14CUX cable into the loom connector on the car
2. Start RoverGauge software
3. Setup RG options settings as follows
a. COM - COMx (use whatever COM port works for you)
b. Speed - mph
c. Temperature – Celsius
d. Parameters to log – all but not road speed or gear selection
4. Set RoverGauge main screen as follows:
a. MAF – Direct
b. Throttle – Absolute
c. Trim – Short Term
5. Turn on the ignition switch and press ‘connect’ to link 14CUX with your laptop.
6. Preferably start the car from cold.
7. Start logging the data (Start Log F5) and drive the car for 15 minutes on a local roads (eg A or B class to get varying running conditions) then stop the car and allow the engine to idle for a further 5 to 10 minutes. (DO NOT TOUCH ANY OF THE CONTROLSAT THIS STAGE)
8. You can now stop logging data by pressing “Stop Log F7”
9. Send the logfiles (held in a sub folder where RoverGauge is) to me (I will msg you my email address)
That's Brilliant Frank. Much appreciated. I'll get straight on it on Saturday. My only concern at the min is driving it from cold. It was almost undrivable last week. Trying to cut out pulling out of junctions etc.2. Start RoverGauge software
3. Setup RG options settings as follows
a. COM - COMx (use whatever COM port works for you)
b. Speed - mph
c. Temperature – Celsius
d. Parameters to log – all but not road speed or gear selection
4. Set RoverGauge main screen as follows:
a. MAF – Direct
b. Throttle – Absolute
c. Trim – Short Term
5. Turn on the ignition switch and press ‘connect’ to link 14CUX with your laptop.
6. Preferably start the car from cold.
7. Start logging the data (Start Log F5) and drive the car for 15 minutes on a local roads (eg A or B class to get varying running conditions) then stop the car and allow the engine to idle for a further 5 to 10 minutes. (DO NOT TOUCH ANY OF THE CONTROLSAT THIS STAGE)
8. You can now stop logging data by pressing “Stop Log F7”
9. Send the logfiles (held in a sub folder where RoverGauge is) to me (I will msg you my email address)
I had it running on the drive last night just up to temp and it was the same. Blip of the throttle would almost cause it to cut out. Then once up to temp. Turn off, restarted and absolutely fine?
Cheers Karl.
Have a look here for TPS values, should be between, 2% and 10% at idle. I would certainly try and get things within tolerance before doing too much trouble shooting.
Aftermarket steppers are well known to be junk sometimes.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Aftermarket steppers are well known to be junk sometimes.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Belle427 said:
Lots of info here on the 14cux too.
http://g33.co.uk/pages/technical-fuel-injection.ht...
May thanks. I'll have a read through that later.http://g33.co.uk/pages/technical-fuel-injection.ht...
Yatesy350i said:
That's Brilliant Frank. Much appreciated. I'll get straight on it on Saturday. My only concern at the min is driving it from cold. It was almost undrivable last week. Trying to cut out pulling out of junctions etc.
I had it running on the drive last night just up to temp and it was the same. Blip of the throttle would almost cause it to cut out. Then once up to temp. Turn off, restarted and absolutely fine?
Cheers Karl.
If you can't run the logfile as described that's ok just do your best attempt. Essentially the drive out is to see the warmup phase and see the extent of the scale/range of values of each parameter. A key test is looking at the data whilst car is warmed up at idle, I need min 3 minutes of thatdata to draw meaningful conclusions.I had it running on the drive last night just up to temp and it was the same. Blip of the throttle would almost cause it to cut out. Then once up to temp. Turn off, restarted and absolutely fine?
Cheers Karl.
blaze_away said:
Yatesy350i said:
That's Brilliant Frank. Much appreciated. I'll get straight on it on Saturday. My only concern at the min is driving it from cold. It was almost undrivable last week. Trying to cut out pulling out of junctions etc.
I had it running on the drive last night just up to temp and it was the same. Blip of the throttle would almost cause it to cut out. Then once up to temp. Turn off, restarted and absolutely fine?
Cheers Karl.
If you can't run the logfile as described that's ok just do your best attempt. Essentially the drive out is to see the warmup phase and see the extent of the scale/range of values of each parameter. A key test is looking at the data whilst car is warmed up at idle, I need min 3 minutes of thatdata to draw meaningful conclusions.I had it running on the drive last night just up to temp and it was the same. Blip of the throttle would almost cause it to cut out. Then once up to temp. Turn off, restarted and absolutely fine?
Cheers Karl.
Just managed to get out for a 20 minute run as the weather has cleared. Think I may have found the issue?
First 15 mins or so from first cold start, no issue with revs or missing in any way. Last 5 mins or so intermittent loss of power when throttle pressed. Almost cut out at traffic lights. Limped it home and left on the drive as recommended idling.
At this point I could concentrate on the screen. Every now and then temp sensor showing 95C dropped to -20C which corresponded with the rise in revs. Sometimes lasted 2-3 seconds. Finally lasted 20 seconds or so with the revs up to around 2k rpm, so I turned the car off.
I assume it's a faulty temp sensor. and as a result the revs lift as the ECU thinks the car is stone cold so is over fuelling?
Happy to send you the file if you can let me have your email address.
I ordered a Lucas SNB802 in the week just in case, hopefully be here on Tuesday.
Many thanks for the heads up. KY.
Yatesy350i said:
Hi Frank
Just managed to get out for a 20 minute run as the weather has cleared. Think I may have found the issue?
First 15 mins or so from first cold start, no issue with revs or missing in any way. Last 5 mins or so intermittent loss of power when throttle pressed. Almost cut out at traffic lights. Limped it home and left on the drive as recommended idling.
At this point I could concentrate on the screen. Every now and then temp sensor showing 95C dropped to -20C which corresponded with the rise in revs. Sometimes lasted 2-3 seconds. Finally lasted 20 seconds or so with the revs up to around 2k rpm, so I turned the car off.
I assume it's a faulty temp sensor. and as a result the revs lift as the ECU thinks the car is stone cold so is over fuelling?
Happy to send you the file if you can let me have your email address.
I ordered a Lucas SNB802 in the week just in case, hopefully be here on Tuesday.
Many thanks for the heads up. KY.
Good find, it could also be bad connection on the sender they do corrode especially as they are 25+ years old now. |Have pm'd you via PH so you'll have my email. send over the file and I will check it out for you.Just managed to get out for a 20 minute run as the weather has cleared. Think I may have found the issue?
First 15 mins or so from first cold start, no issue with revs or missing in any way. Last 5 mins or so intermittent loss of power when throttle pressed. Almost cut out at traffic lights. Limped it home and left on the drive as recommended idling.
At this point I could concentrate on the screen. Every now and then temp sensor showing 95C dropped to -20C which corresponded with the rise in revs. Sometimes lasted 2-3 seconds. Finally lasted 20 seconds or so with the revs up to around 2k rpm, so I turned the car off.
I assume it's a faulty temp sensor. and as a result the revs lift as the ECU thinks the car is stone cold so is over fuelling?
Happy to send you the file if you can let me have your email address.
I ordered a Lucas SNB802 in the week just in case, hopefully be here on Tuesday.
Many thanks for the heads up. KY.
Belle427 said:
Hopefully an easy fix then, maybe a loose or corroded connection.
Thank you and Frank for all the help and advice. I think it was a combination of an intermittent sensor and high resistance connections due to corrosion. I tested the old sensor in hot water with a DVM last night and it did drop off but only once. So as a precaution while swapping the sensor out, I cleaned the terminals on the sensor plug as well.Managed to get it out for 30 mins at lunchtime and it seems to be running really well. Goes like stink. Just need to calm that exhaust BOOM down a bit now.
Had the Rovergauge running for the duration and all looks well.
Cheers Karl.
Morning All
Had a cracking run out on Saturday to the Ponderosa in North Wales. The car performed faultlessly, Very impressed with the acceleration in 5th. Did around 170 mile trip.
Had a quick blast out yesterday as the weather in Staffordshire was surprisingly good for a second day. The holding of the slightly high idle was back again. No other issues just seemed to take a while to drop down from 1500 rpm to idle?
I adjusted the idle via the Plenum screw when I got back and notice there is almost no resistance when turning the screw. 1 full rotation seems to alter the rpm by around 100rpm and hold. But the screw seems very loose. Is this normal?
Cheers Karl..
Had a cracking run out on Saturday to the Ponderosa in North Wales. The car performed faultlessly, Very impressed with the acceleration in 5th. Did around 170 mile trip.
Had a quick blast out yesterday as the weather in Staffordshire was surprisingly good for a second day. The holding of the slightly high idle was back again. No other issues just seemed to take a while to drop down from 1500 rpm to idle?
I adjusted the idle via the Plenum screw when I got back and notice there is almost no resistance when turning the screw. 1 full rotation seems to alter the rpm by around 100rpm and hold. But the screw seems very loose. Is this normal?
Cheers Karl..
It should have a little resistance or it could vibrate either way, seem to remember mine was fairly tight to turn.
You should still clean the stepper properly and set the base idle as a basic check, all the info is below midway down the page.
You can just clamp the stepper hose to make the adjustment if you dont have materials to make a bung.
http://g33.co.uk/pages/technical-fuel-injection.ht...
You should still clean the stepper properly and set the base idle as a basic check, all the info is below midway down the page.
You can just clamp the stepper hose to make the adjustment if you dont have materials to make a bung.
http://g33.co.uk/pages/technical-fuel-injection.ht...
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