Discussion
Time to sort out the rough running I've been having over the last few weeks.
The car will randomly run rough, and then suddenly as if someone has flicked a switch, it runs fine.
When it runs rough, the car is hesitant to accelerate and refuses to go above 80mph, sir. Then it will run fine again.
Borrowed a multimeter, here is what i've checked so far
Checked CTS. Disconnected it and checked resistance at hot and cold and is within normal values.
Removed ECU multiplug, again checked resistance between the CTS pin and ground. Also correct value.
Tested the afm according to instructions here:
http://www.vintagemodelairplane.com/pages/Rover_Te...
With ecu plug off and ignition on (immobiliser disabled):
Checked resistances of pins as per instructions on page 2 Got correct values.
At this point I got home, so only had a £15 maplin multimeter, which is a bit suspect. Considering it measured the car battery at 21 volts, i'll leave it here.
I did continue but I'll have to re-check them with a proper fluke meter, as the meter I used was crap
Any ideas?
The car will randomly run rough, and then suddenly as if someone has flicked a switch, it runs fine.
When it runs rough, the car is hesitant to accelerate and refuses to go above 80mph, sir. Then it will run fine again.
Borrowed a multimeter, here is what i've checked so far
Checked CTS. Disconnected it and checked resistance at hot and cold and is within normal values.
Removed ECU multiplug, again checked resistance between the CTS pin and ground. Also correct value.
Tested the afm according to instructions here:
http://www.vintagemodelairplane.com/pages/Rover_Te...
With ecu plug off and ignition on (immobiliser disabled):
Checked resistances of pins as per instructions on page 2 Got correct values.
At this point I got home, so only had a £15 maplin multimeter, which is a bit suspect. Considering it measured the car battery at 21 volts, i'll leave it here.
I did continue but I'll have to re-check them with a proper fluke meter, as the meter I used was crap
Any ideas?
Edited by MethylatedSpirit on Sunday 19th June 23:26
If you can place the ECU in the footwell where you can access it with a hammer...Well not quite a hammer but more of the handle of a screwdriver..when it is playing up give it a tap with the screwdriver handle..If it stops happening then the ECU needs a rebuild..
I know someone who did this and since the ECU was rebuilt the car has been smooth and actually more economical...
I know someone who did this and since the ECU was rebuilt the car has been smooth and actually more economical...
mrzigazaga said:
If you can place the ECU in the footwell where you can access it with a hammer...Well not quite a hammer but more of the handle of a screwdriver..when it is playing up give it a tap with the screwdriver handle..If it stops happening then the ECU needs a rebuild..
I know someone who did this and since the ECU was rebuilt the car has been smooth and actually more economical...
I did try that! It didn't work.I know someone who did this and since the ECU was rebuilt the car has been smooth and actually more economical...
Anyone got a 350i that I can swap the ECU and AFM temporally to see if the problem goes away (Glasgow area)
There is a AFM going on EvilBay. I could just buy and try, it's good as a spare and I'd get the same back if I auctioned it again.... http://www.ebay.co.uk/itm/371652547861?_trksid=p20...
Hi mate
A couple of things....Have you changed the spark plug leads..Especially the king lead as this often gets left as the ones supplied are too short...
And do you have a solid state fuel pressure regulator or an adjustable one?
This happened to me when i turned the fuel pressure up on my adjustable by 2psi which doesn't sound much but the car wouldn't go over 70 but sped up a bit when i backed off the throttle...
Also check the wire under the rubber boot of the CTS as mine was playing up and i replaced it a couple of times with no positive result...I then found this...
If you have a solid state FPR then try to get the fuel pressure checked as the diaphragm inside could be failing....
Cheers
Ziga
A couple of things....Have you changed the spark plug leads..Especially the king lead as this often gets left as the ones supplied are too short...
And do you have a solid state fuel pressure regulator or an adjustable one?
This happened to me when i turned the fuel pressure up on my adjustable by 2psi which doesn't sound much but the car wouldn't go over 70 but sped up a bit when i backed off the throttle...
Also check the wire under the rubber boot of the CTS as mine was playing up and i replaced it a couple of times with no positive result...I then found this...
If you have a solid state FPR then try to get the fuel pressure checked as the diaphragm inside could be failing....
Cheers
Ziga
Anyone got a 350i flapper near Glasgow that I can try various components so that I can try and narrow this down?
Took it to dreadnaught TVR in Callender today and we spent 4 hours testing various components.
Car runs rough -at idle and partial throttle- until completely hot. As quick as snapping your fingers; the engine note will change, the idle will change slightly and the car runs smooth as butter.
So far we've/ i've replaced & checked:
Connected afm to dealer test unit. Seems okay
Checked wiring for cts and connected to test unit. Also measured resistance at plug and ecu. Seems okay
Connected throttle pot to test unit & read with voltmeter. Read out of spec. Re-adjusted throttle pot to give correct signal across the range. Made no difference.
New coil. Gives a big, fat spark. Seems okay
New ignition leads. Tested spark on all 8. Has a extremely good spark on all 8.
Checked all wiring and earths, pulled back boots and checked connections. Seems okay.
Test drove it, the car decided to behave itself and run fine!! (It must have known!)
Suggestions from me/Brian of things to try?:
Auxiliary Air Valve may be getting getting stuck, as it only runs fine when this part is really, really hot (Apparently this part is very simple and reliable? And it's very expensive)
Try another afm as my one has been "cheated" with evidence of silicone to close it shut
Trying another ECU. Might be dry solder joints?
He said he was embarrassed that he was completely stumped (after 4 hours of us both testing components and checking) that he couldn't give a definitive cause of it running s
te.
Took it to dreadnaught TVR in Callender today and we spent 4 hours testing various components.
Car runs rough -at idle and partial throttle- until completely hot. As quick as snapping your fingers; the engine note will change, the idle will change slightly and the car runs smooth as butter.
So far we've/ i've replaced & checked:
Connected afm to dealer test unit. Seems okay
Checked wiring for cts and connected to test unit. Also measured resistance at plug and ecu. Seems okay
Connected throttle pot to test unit & read with voltmeter. Read out of spec. Re-adjusted throttle pot to give correct signal across the range. Made no difference.
New coil. Gives a big, fat spark. Seems okay
New ignition leads. Tested spark on all 8. Has a extremely good spark on all 8.
Checked all wiring and earths, pulled back boots and checked connections. Seems okay.
Test drove it, the car decided to behave itself and run fine!! (It must have known!)
Suggestions from me/Brian of things to try?:
Auxiliary Air Valve may be getting getting stuck, as it only runs fine when this part is really, really hot (Apparently this part is very simple and reliable? And it's very expensive)
Try another afm as my one has been "cheated" with evidence of silicone to close it shut
Trying another ECU. Might be dry solder joints?
He said he was embarrassed that he was completely stumped (after 4 hours of us both testing components and checking) that he couldn't give a definitive cause of it running s
te.Edited by MethylatedSpirit on Wednesday 6th July 22:00
Hi mate
The AFM was probably fiddled with to try to sort this issue out..Unfortunately like most random fixes it just makes things worst..It could be an ECU issue...Have you tried the simple stuff like cleaning up the pins on the ECU connector plug?...
Do you have an adjustable fuel regulator?...can you check the fuel pressure?..Maybe a gauge on the cold start feed.
I had a similar issue when i turned up the fuel pressure by 2psi...The car would not go over 70mph and when you backed off it surged like the timing was out...
If you have a solid state FPR again check the fuel pressure as they can fail..Sounds more like a fuel problem....
Ziga
The AFM was probably fiddled with to try to sort this issue out..Unfortunately like most random fixes it just makes things worst..It could be an ECU issue...Have you tried the simple stuff like cleaning up the pins on the ECU connector plug?...
Do you have an adjustable fuel regulator?...can you check the fuel pressure?..Maybe a gauge on the cold start feed.
I had a similar issue when i turned up the fuel pressure by 2psi...The car would not go over 70mph and when you backed off it surged like the timing was out...
If you have a solid state FPR again check the fuel pressure as they can fail..Sounds more like a fuel problem....
Ziga
Not an expert so just thinking of easy things to check:
All earths to coil, AFM, engine - could one be loose?
Loose multiplug on ECU?
Ignition amp on dissy playing up?
Is there any lateral movement in dissy shaft - i.e wear causing rotor arm to move off centre?
Dodgy earth or power feed to the fuel pump causing variable fuel pressure?
Pressure regulator sticking and causing fueling issue?
Sticking bufferfly on AFM?
To eliminate extra air valve could it be temporary blanked off to see if it is the culprit?
Straws - clutching at...
I took 3 months to find an intermittent misfire on my 350i last year - turned out to be a combination of worn dissy, then failed new dissy plus failing coil and failing HT leads.
Cheers.
All earths to coil, AFM, engine - could one be loose?
Loose multiplug on ECU?
Ignition amp on dissy playing up?
Is there any lateral movement in dissy shaft - i.e wear causing rotor arm to move off centre?
Dodgy earth or power feed to the fuel pump causing variable fuel pressure?
Pressure regulator sticking and causing fueling issue?
Sticking bufferfly on AFM?
To eliminate extra air valve could it be temporary blanked off to see if it is the culprit?
Straws - clutching at...
I took 3 months to find an intermittent misfire on my 350i last year - turned out to be a combination of worn dissy, then failed new dissy plus failing coil and failing HT leads.
Cheers.
Don't forget the earth strap underneath from the gearbox to chassis.
If you suspect the EAV then you can remove the pipe and plug it. You don't need it this time of year really.
If you suspect the fuelling/AFM/ECU then get an oscilloscope on the injector pulses (easy enough to attach extra cables to the plugs at the engine end) and monitor the pulses - how wide they are especially.
Also check the compression when cold and then when hot - I think I have a sticky valve on number 6 that unsticks after a mile's running (so not worth the bother of fixing really). It shows up as low compression.
If you suspect the EAV then you can remove the pipe and plug it. You don't need it this time of year really.
If you suspect the fuelling/AFM/ECU then get an oscilloscope on the injector pulses (easy enough to attach extra cables to the plugs at the engine end) and monitor the pulses - how wide they are especially.
Also check the compression when cold and then when hot - I think I have a sticky valve on number 6 that unsticks after a mile's running (so not worth the bother of fixing really). It shows up as low compression.
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