Discussion
I have been having murders with this car since the engine has been rebuilt. In hindsight, I wish I had just had a new V8D 4.6 put in but there you go.
The first time it was rebuilt using new piston rings, the bores didn't seal and 3000 miles later it was using at least a litre of oil every tank of fuel and showing signs of HG failure due to oil in the bores pushing past the HG.
The garage, to their credit, took it back without argument and rebuilt it again, this time boring it out and using oversized pistons and rings.
Since then, the car has been using a lot of oil still - I have done 500 miles in it since the second rebuild. There have been other issues. The day after I got the car back it broke down due to losing spark plugs one by one and an overfuelling issue was suspected, even though there were no fault codes. The left hand lambda was changed and a new ECU chip from Power was installed along with a set of new plugs. The whole ignition system has been renewed with amp, dizzy cap, rotor arm (genuine Lucas), coil and leads.
The car still misfires occasionally and I am getting backfiring due to unburnt fuel. Could this be a problem with the distributor causing weak spark as there does seem to be some movement in it?
Rovergauge reckons the left bank is running richer than the right and that is the side with the new lambda. I am now at a loss and am losing confidence in the garage to put it right. I am also concerned that if it is misfiring and overfuelling then the new engine won't have a hope in hell of sealing as the fuel is contaminating the oil. I am pretty much at the end of my tether with the car to be honest.
Roverguage screenshot. The fuelling looks fine at idle as it is switching back and forth but the long term looks worrying. It has come down since yesterday, it was showing +70% on the left bank.
The first time it was rebuilt using new piston rings, the bores didn't seal and 3000 miles later it was using at least a litre of oil every tank of fuel and showing signs of HG failure due to oil in the bores pushing past the HG.
The garage, to their credit, took it back without argument and rebuilt it again, this time boring it out and using oversized pistons and rings.
Since then, the car has been using a lot of oil still - I have done 500 miles in it since the second rebuild. There have been other issues. The day after I got the car back it broke down due to losing spark plugs one by one and an overfuelling issue was suspected, even though there were no fault codes. The left hand lambda was changed and a new ECU chip from Power was installed along with a set of new plugs. The whole ignition system has been renewed with amp, dizzy cap, rotor arm (genuine Lucas), coil and leads.
The car still misfires occasionally and I am getting backfiring due to unburnt fuel. Could this be a problem with the distributor causing weak spark as there does seem to be some movement in it?
Rovergauge reckons the left bank is running richer than the right and that is the side with the new lambda. I am now at a loss and am losing confidence in the garage to put it right. I am also concerned that if it is misfiring and overfuelling then the new engine won't have a hope in hell of sealing as the fuel is contaminating the oil. I am pretty much at the end of my tether with the car to be honest.
Roverguage screenshot. The fuelling looks fine at idle as it is switching back and forth but the long term looks worrying. It has come down since yesterday, it was showing +70% on the left bank.
Dont forget long term trim is a base setting at idle only- and it sets the basic fueling up to 3400 rpm- above that trim is not applied. 70% is not the end of the world- it just means either the maps not quite right or a sensor input is out a bit. The problem with plugging in different maps, you dont really know what's going on as the ECU simply tries to correct it on the fly if its wrong . In an ideal world you would put the car on a rolling road, and then reset the ECU so there was no long term trim, then tweak the map until the lambdas just switch are various RPM ranges. If you dont let the car idle, it wont set the long term trim. this will minimise the need for extra long term trim.
Back to the actual fault- you really need a gas analyser on a rolling road to get a true picture- the exhaust content will vary if its a misfire, under fuelling or over fuelling as the CO, NOX and HC readings vary. A lambda probe only measures unused oxygen in the exhaust, so its limited what it can tell you. Another option is to stump up £150 or so and fit a A/F ratio gauge to the car with wideband Lambda- its well worth the money if you are not running a stock engine. Steve Sprint fitted an analogue one to his Griff to replace the volt meter- it was a work of art to match the other gauges and even had the TVR logo.
Back to the actual fault- you really need a gas analyser on a rolling road to get a true picture- the exhaust content will vary if its a misfire, under fuelling or over fuelling as the CO, NOX and HC readings vary. A lambda probe only measures unused oxygen in the exhaust, so its limited what it can tell you. Another option is to stump up £150 or so and fit a A/F ratio gauge to the car with wideband Lambda- its well worth the money if you are not running a stock engine. Steve Sprint fitted an analogue one to his Griff to replace the volt meter- it was a work of art to match the other gauges and even had the TVR logo.
Thanks for the explanation.
The car was put on a gas analyser the other day (not on a rolling road) and results are as follows:-
Fast idle: CO 0.08 HC 32ppm of a permitted 0.20 CO and 200ppm HC.
Natural idle 0.01 of a permitted 0.30 CO.
The Lamda reading was 1.007 of a permitted range of 0.97 to 1.03.
Obviously it was running OK at that point. I drove it home and it lost a plug and I couldn't get it back. A new spark plug sorted it and it ran beautifully. It was running on its original rotor arm and a pretty worn cap so these were changed. When the rotor arm was changed it was noticed that there was an awful lot of free play in the distributor which could well be knocking the timing all over the place.
The spark plugs are all contaminated with carbon deposits which means there is a problem somewhere.
It's running a standard 450CAT map from Power. It does run better than it did with the original chip.
It's getting a new distributor later this week and the garage are going to keep it and run it for a bit as I am sick of picking it up, only for it to go wrong again.
The car was put on a gas analyser the other day (not on a rolling road) and results are as follows:-
Fast idle: CO 0.08 HC 32ppm of a permitted 0.20 CO and 200ppm HC.
Natural idle 0.01 of a permitted 0.30 CO.
The Lamda reading was 1.007 of a permitted range of 0.97 to 1.03.
Obviously it was running OK at that point. I drove it home and it lost a plug and I couldn't get it back. A new spark plug sorted it and it ran beautifully. It was running on its original rotor arm and a pretty worn cap so these were changed. When the rotor arm was changed it was noticed that there was an awful lot of free play in the distributor which could well be knocking the timing all over the place.
The spark plugs are all contaminated with carbon deposits which means there is a problem somewhere.
It's running a standard 450CAT map from Power. It does run better than it did with the original chip.
It's getting a new distributor later this week and the garage are going to keep it and run it for a bit as I am sick of picking it up, only for it to go wrong again.
Edited by Trevor450 on Wednesday 2nd July 19:27
A lot of that play in the dizzy is the advance mechanism that slops around all over the place if the dizzy is not spinning. It all tightens up as the RPM rises above idle- but you can see if there are issues with a strobe on the timing marks- if they dance around at a fixed RPM (called timing scatter) then wear is an issue.
blitzracing said:
A lot of that play in the dizzy is the advance mechanism that slops around all over the place if the dizzy is not spinning. It all tightens up as the RPM rises above idle- but you can see if there are issues with a strobe on the timing marks- if they dance around at a fixed RPM (called timing scatter) then wear is an issue.
When I mean play, I mean a quarter turn. That can't be right surely? There is a load of float up and down too.Sorry to hijack this, but I have been having 'issues' and have nearly ironed them out now. The only thing now is my long term is now at -100% on both banks, It is no longer running mega rich after repairing the Left bank Lambda wiring. My suspicion is an AFM fault as I have various slight flat spots through the rev range and from idle if I just move the throttle it hesitates slightly and the TPS is working fine (I think), or could it be a sensor fault?
Sorry again
Jamie
Sorry again
Jamie
blitzracing said:
You can turn the rotor against the advance springs, thats how the timing works, but it should spring back.
It was floppy which doesn't sound good. It's getting a new one anyway. My specialist wasn't happy with its condition. My AFM is fine. It was substituted for a known working one and it made no difference. I'm just wondering if there is a load of oil in the pre cats from the last failure that is poisoning the lambdas. You would have thought it wouldn't pass an emissions test if that were the case though.
mattrosersv said:
Hi Jamie (and anyone else),
I have both the original AFM and an unused £50 ebay jobbie on the shelf in my garage. Happy to loan them out to anyone should they want to do some testing.
Matt (Andover, Hants)
Ill take you up on that- but Ive loaned my datalogger out for a few weeks so I wont be able to give results to near the end of the month. I can bench test the two together, check the reponses, and apply a bit of heat and see if the output moves.I have both the original AFM and an unused £50 ebay jobbie on the shelf in my garage. Happy to loan them out to anyone should they want to do some testing.
Matt (Andover, Hants)
The engine barely has any original parts left. The top end is completely new as well apart from the heads but they were rebuilt with new seals etc.
In hindsight, I wish I had bought a V8 Developments 4.6 performance short block and that may still be an option if this rebuild has failed too. It compression tested fine the other day but whether that is down to oil in the bores or not I don't know.
To my knowledge the engine has had: -
Bored with oversize pistons and rings.
Crank balanced and new shells.
New 885 cam and cam shells.
New oil pump.
Three new liners.
Rockers, lifters etc.
Valve stem seals.
In hindsight, I wish I had bought a V8 Developments 4.6 performance short block and that may still be an option if this rebuild has failed too. It compression tested fine the other day but whether that is down to oil in the bores or not I don't know.
To my knowledge the engine has had: -
Bored with oversize pistons and rings.
Crank balanced and new shells.
New 885 cam and cam shells.
New oil pump.
Three new liners.
Rockers, lifters etc.
Valve stem seals.
Edited by Trevor450 on Friday 4th July 12:22
Gassing Station | Chimaera | Top of Page | What's New | My Stuff