Still stalling when warm

[STE VR]

...sorry but this is ongoing from the 'ignition module' thread. I was informed they(the garage) had found my stalling when hot fault by finding the vacuum advance diaphragm was shot. This was replaced but was not the fault after all . The problem is now that when the car is cold(rich mixture) all is pretty good,idles, starts ok. When the engine is warming/warm(lean mixture) the engine splutters and dies, also very very hard to restart. If we disconnect the ecu coolent temp sensor(when warm) the car idles fine but very rich smell of petrol and starts first time. The coolent temp sensor has been replaced twice and the wiring checked back to the ecu, so we can rule that out. Any ideas/pointers cos i'm getting really really really pd off now and want my p&j away from that garage and back home where she belongs.

Many thanks

Steve

[The Aardvark]

Sounds like we have the same issue - not sure whether you've seen these, one historical, one I started on Sunday.

http://www.pistonheads.co.uk/gassing/topic.asp?h=0...

http://www.pistonheads.co.uk/gassing/topic.asp?h=0...

Currently spoiling my enjoyment of the car. Have had a local specialist look at it and change lamdas, and coolant sensor (as well as other bits, sorry, not that technical) as well as reset ECU twice. Problem seemed to go away but returned over the weekend.
Will be going back to specialist shortly, who said he's seen idleing issues before but not necessarily this one - thinks that it could be a wiring problem.
Have complete faith in what he's doing - so will keep you posted if anything is diagnosed!

[STE VR]

Please do. I've now changed practically everything on the car now(inc ecu), no air leaks etc, and still no bloody clue!

Cheers

Steve

[AlexanderV8]

I had your symptons almost exactly & the fault turned out to be the rotor arm. There are some Lucas 'replacements' around which don't perform.
My engine ran fine until warm, when the misfiring got worse, until it stalled at junctions & was difficult to restart. Needed to be nursed home and temperature got way too high.
Secondary problems associated with this are plugs fouling with fuel causing more starting/running problems.

It's easy to get carried away & start suspecting everything. One local TVR 'specialist' to me couldn't find this problem & cost me a fair bit of money in the process. various temp sensors were changed etc.

Ensure you have a genuine rotor arm and don't judge it on condition. I had already checked mine and it looked fine. I think it may not have been sitting at the correct height in the cap.

FYI, the 'specialist' also changed the coil, coil amp and lead set.

Moral of the story should be try the simple stuff first - rotor arm & plugs before suspecting the rest!

Cheers & good luck,

Mick

[STE VR]

Thanks Mick, i see you have also been through the so-called 'specialist' experience. They have told me they have replaced all these bits and pieces but i'm not totally convinced. Will get it back off them this weekend and start looking at myself(maybe with the help of Chassis33) Failing that it's off the road for a while......

Cheers

Steve

[AlexanderV8]

Hi Steve,
The problem with the rotor arm issue is that even some 'specialists' either discount it as the cause, or have a stock of new so-called 'replacements' which may be used in attempted fault diagnosis (by way of swap-out) but are then subsequently found not to change the symptoms and therefore discounted!

The TVR Centre at Barnet (now Trimar) were the ones who understood & rectified the problem. They bought a stock of known good arms because they had come across this before. My car hasn't missed a beat since this. Like you, I was at my wits end and frightened to take the car out at all for quite a while. I was seriously considering offloading it.

I hope your fault proves to be as simply cured.
Mick

[bam50]

Steve, have you got any mates with a Chimaera/Griff who'd be prepared to temporarily swap some simple parts? There's nothing worse than trying to fault find with faulty new bits, if that's what it is. I was thinking along the lines of swap a bit and then go for a drive to see what happens to what car. Good luck.

[blitzracing]

You really cant be sure its simply running too lean because disconnecting the temperature sensor makes it run better. This is a real sledge hammer approach to whats a basically a finely balanced system. A better approach is to disconnect the vaccume pipe to the fuel regulator, and block it off so no air getes into the plenum. This will raise the fuel pressure (at tickover) and see the effect. The ECU is pretty clever, and should compensate for the increased fuel pressure within 30 seconds or so, and the idle should become stable and even. This will at least tell you if its mixture related, and the ECU/lambda feedback is working.

You can download the ECU manual here:


http://www.g33.co.uk/images/PDFS/14cux_fuel_inject...

Mark

[Podie]

AlexanderV8 said:

I had your symptons almost exactly & the fault turned out to be the rotor arm. There are some Lucas 'replacements' around which don't perform.
My engine ran fine until warm, when the misfiring got worse, until it stalled at junctions & was difficult to restart. Needed to be nursed home and temperature got way too high.
Secondary problems associated with this are plugs fouling with fuel causing more starting/running problems.

It's easy to get carried away & start suspecting everything. One local TVR 'specialist' to me couldn't find this problem & cost me a fair bit of money in the process. various temp sensors were changed etc.

Ensure you have a genuine rotor arm and don't judge it on condition. I had already checked mine and it looked fine. I think it may not have been sitting at the correct height in the cap.

FYI, the 'specialist' also changed the coil, coil amp and lead set.

Moral of the story should be try the simple stuff first - rotor arm & plugs before suspecting the rest!

Cheers & good luck,

Mick

Yep, had this on my Chimaera once. Rotor arm was replaced with a pattern part and cuased this problem.

[T_Pot]

steve, i have no idea where you live sorry, but if your near me in south wales, then ill happily swap parts on my chim so you can test yours.

[STE VR]

Thanks very much for the offer TPot, very much appreciated, but i've now changed all the parts with another working TVR including,

ECU
AFM
Coil
Amp
Plugs
Coolent & Fuel temp sensors
Dizzy cap
Rotor Arm
New advance unit
Leads
Throttle pot
Stepper

Still not working right!!!

Cheers,

Steve

[T_Pot]

ok, im no mechanic, but have you changed fuel filters? checked timing and fuel related issues ?

sorry if im teaching gran to suck eggs, just trying an idiots point of view lol

[STE VR]

Trust me, you are not teaching me to suck eggs!, and your input is gratefully received, the fuel pressure is fine and the timing has been setup correctly even though the marks on the pulley are wrong(so they tell me).

Thanks

Steve

[T_Pot]

STE VR said:

Trust me, you are not teaching me to suck eggs!, and your input is gratefully received, the fuel pressure is fine and the timing has been setup correctly even though the marks on the pulley are wrong(so they tell me).

Thanks

Steve

just out of interest, have you thought about timing it to the marks, in case they are right?

it sounds to me, as the fuel mixture is too weak once warm

[STE VR]

They have done static timing, which i think, is the old fashioned way of getting No1 cylinder to the top of its stroke and setting the distributer that way.... Not sure how you test for a weak mixture when warm though..i'm sure some 'slightly' more experienced ph'ers will tell me tho!!

Thanks

Steve

[350Matt]

If the timing marks on the pulley are out, ( not uncommon) then you need to make new ones so that the timing can be set with a timing light correctly.

Alternatively you could take the rougher approach and if its not already pinking, just advance it a bit

You can check fuel mix with a tailpipe probe / gas analyser

Matt

[blitzracing]

Have you tried winding the base idle screw up a bit ? Its the hex head adjustment on the right hand side of the throttle body area of the plenum chamber. This works in conjuction with the stepper motor, by providing just enough air to keep the engine ticking over when warm, under no load. The stepper only adds a bit more air if the engines cold or under a bit of load (like air con).To set it up, get the engine warm, and block off the black air feed hose to the stepper. You can pull the pipe off at the throttle body pipe and use duck tape to block BOTH free ends and make it air tight or put in a bung. Then get someone to start the car whilst you keep it running on the throttle lever bit on the plenum, as it probibly wont tick over. With the other hand, then wind up the base idle screw (some nasty imperial hex key- none of my metric ones fit it) untill the car ticks over at 800 rpm plus. You can then give it a run like this to check it does not die on you. If its stable then remove the duck tape, and reconnect the pipework. The idle may rise a 100 rpm or so dependent on the ECU fuel map as the stepper tries to keep it at around 900 rpm, but it should not stall. However if you have to screw the base idle up a long way you may find the car ticks over too fast before dropping the rpm at standstill and it can also cause the ECU to generate fault codes. If it still dies, it is likely there is something fundimentally wrong with the idle mixture / control. Example an over rich mixture can cause the idle to vary wildly dependent on how much excess fuel is in the inlet manifold, before it clears when you open the throttle under load. The ECU should never allow this to happen normally, unless you are running the non catalyst fuel map, and the CO adjustment is wrong on the air flow meter.

Pic's and details here:

http://www.g33.co.uk/fuel_injection.htm

Let us know the results

Mark

[STE VR]

Ok, got car back from garage today(i took it because they are getting nowhere). Original fault was no tickover when warm. Long story but nearly EVERYTHING has been replaced, then replaced again. Symptoms now are: running exceptionally rich, very lumpy tickover(but does tickover now cold or warm). Revs up ok but not perfect but take it for a run and it starts to miss about 3,500 rpm. Stinks of fuel all the time, eating juice like mad, brand new plugs now very sooty.

Items changed:
ECU, Rotor arm(genuine Lucas, trust me!!) x4, dizzy cap x2, all ht leads x3, afm x1, ignition module x3, plugs x2, stepper motor x3, coolent sensor x2, fuel temp sensor x1, coil inc genuine bosch x3, vacuum advance unit x1. plus some more bits i,ve probably forgotten about!!. Lambda sensors have not been replaced but they assure me they test perfectly.

They suggested the weights in the dizzy might be seized? does this make sense?

Any ideas really appreciated as i'm running this as an everyday car on a budget. Failing that does anybody know where a good place to take it might be in the wirral area?

HELP, i'm goin a bit

[Ribol]

Weights in the dizzy are not going to cause what you describe here.

If we are clutching at straws have you checked that the ECU to ECU plug connections are all good, no pins come loose or anything like that? Might have been disturbed when pluging in/out a few times.

[STE VR]

Not 100% sure but all tests were done at ecu plug just to prove wiring. all contacts seem nice and clean.

Thanks

Steve