Not running right mixture / timing? 2.9 cologne
Discussion
I'm new to the 2.9, but it sounds like it's not getting enough fuel. The ignition timing won't suddenly change, but fuel pressure could impact your ratio, as could a vacuum leak, but that usually comes hand in hand with a high idle. If you unplug the throttle position sensor, does it change anything? That is a known point of failure and it can be tested with a volt meter. If the fuel regulator goes south, you can usually smell petrol in the vacuum line, so that's an easy check.
Mine was flaky until I replaced the PCV vacuum hose with something that could handle a vacuum without collapsing, but my symptoms were a dead zone just off idle.
I would unplug the TPS and go for a spin. It won't be perfect because the ECU will be using defaults, but if it feels better you might be in the right area.
Mine was flaky until I replaced the PCV vacuum hose with something that could handle a vacuum without collapsing, but my symptoms were a dead zone just off idle.
I would unplug the TPS and go for a spin. It won't be perfect because the ECU will be using defaults, but if it feels better you might be in the right area.
Mixture is adjustable at the AFMs. You will notice two circular holes on the rear of them as mounted in the car with an Allen key head inside. These bypass the AFM and allow mixture to be adjusted with the ECU sensing flow through the AFM and adjusting fuel flow to that flow then more bleed equals weaker mixture. Set up is provided in the car mechanics article. If you don't have this pm me and I'll email it or I think it is on tvrgit's website for download. This said they should not wander so too lean is likely to be a leak between the AFM and the throttle body. This may not show at idle as the ISCV may have sufficient movement to compensate if it is small enough but it would show on running at low throttle. Equally at full throttle the effect would be reduced and therefore little effect would be seen. I suggest you give the flexible tubes here a good check over
I'd read the fault codes first with http://www.amazon.co.uk/Gunson-77032-Fault-Code-Re.... I found mine for £35 which was money well spent.
Assuming no fault codes: Getting the emissions tested will show if the car is running rich/lean at idle. The limit for CO at idle is <3.5% but cars run best around 1.4%. Are you friendly with your local MOT testing station/garage? They could test this for you easily enough and cost should be low. If the emissions are out you (or the garage) could start by adjusting the flow meters but you must adjust both equally to ensure they stay in balance.
Another alternative is to buy a Gunson gas tester to test the emissions. I got mine a year ago from halfords for £80. This would allow you to test the emissions at your leisure. There are some tricks to using these devices so let me know if you buy one and I'll fill in on some of my experiences.
Although going to your local garage or using a Gastester is a good option to adjust the fuelling at idle it does n't show fuelling throughout the rev range/under load. If your car is rich at idle now and you adjust the AFMs to be bang on at idle you may then be run lean at the top end. From my experience fiddling around with emissions - you need time to check various different settings, road test and repeat - because you will only be getting part of the picture and ultimately your money could be wasted.
My recommendation is to get your car down to a rolling road who can check emissions and fuelling across the rev range and adjust the AFMs to suit. I've had experience with Austec in Crawley and Circuit Motors at Castle Combe - both did a great job on my car. These guys would also be able to telling you if a sensor is failing etc.
A couple of other points to bear in mind:
Both AFMs are equipped with a temp sensor but the car only uses the temp sensor in one of the them. Have you tried swapping the plugs going into the AFMs? if just one is dodgey this may improve running.
Is your car fitted with an adjustable fuel pressure regulator? If so this is another area that can go out of adjustment - and another area that I reccommend you get over to a rolling road to get checked.
In summary I'd:
1) Read fault codes.
2) Swap leads to the AFMs and see if this makes any difference
3) Maybe get local garage to check emissions (or skip and go straight to 4)
4) Get the car booked into a rolling road
Ralph
Assuming no fault codes: Getting the emissions tested will show if the car is running rich/lean at idle. The limit for CO at idle is <3.5% but cars run best around 1.4%. Are you friendly with your local MOT testing station/garage? They could test this for you easily enough and cost should be low. If the emissions are out you (or the garage) could start by adjusting the flow meters but you must adjust both equally to ensure they stay in balance.
Another alternative is to buy a Gunson gas tester to test the emissions. I got mine a year ago from halfords for £80. This would allow you to test the emissions at your leisure. There are some tricks to using these devices so let me know if you buy one and I'll fill in on some of my experiences.
Although going to your local garage or using a Gastester is a good option to adjust the fuelling at idle it does n't show fuelling throughout the rev range/under load. If your car is rich at idle now and you adjust the AFMs to be bang on at idle you may then be run lean at the top end. From my experience fiddling around with emissions - you need time to check various different settings, road test and repeat - because you will only be getting part of the picture and ultimately your money could be wasted.
My recommendation is to get your car down to a rolling road who can check emissions and fuelling across the rev range and adjust the AFMs to suit. I've had experience with Austec in Crawley and Circuit Motors at Castle Combe - both did a great job on my car. These guys would also be able to telling you if a sensor is failing etc.
A couple of other points to bear in mind:
Both AFMs are equipped with a temp sensor but the car only uses the temp sensor in one of the them. Have you tried swapping the plugs going into the AFMs? if just one is dodgey this may improve running.
Is your car fitted with an adjustable fuel pressure regulator? If so this is another area that can go out of adjustment - and another area that I reccommend you get over to a rolling road to get checked.
In summary I'd:
1) Read fault codes.
2) Swap leads to the AFMs and see if this makes any difference
3) Maybe get local garage to check emissions (or skip and go straight to 4)
4) Get the car booked into a rolling road
Ralph
Steve, is this only since gearbox work, was engine removed to get at gearbox?
If so, it may be obvious, but something more than likely has been disturbed/broken/knocked/damaged?
I'd start with the simple things, good "wiggle" of all the multi-plugs, hoses from air filter to plenum could have pulled off if engine leant backwards to remove gearbox, distributor module could have been damaged, timing could be way out (if dizzy removed) etc. etc.
Good luck
I gave in today having swapped all the plugs, pulled every connector / plug apart, cleaned up the dizzy, tightened up the vac pipes, remade every earth strap etc etc.
I have settled for retarding the ignition 4 degrees at the 'octane' plug. I figure with a load of S-perts around me for the next few days - it'll be an easy fix for one of em?
what do you recon?
I have settled for retarding the ignition 4 degrees at the 'octane' plug. I figure with a load of S-perts around me for the next few days - it'll be an easy fix for one of em?
what do you recon?
Steve, I may be wrong, but I don't think anyone will be bringing an exhaust gas analyzer / CO meter / diagnostic computer thingy on tour.
Best get timing & mixture set up properly at your local friendly tuners.
Geoff, the boss at my local MOT place used to fettle the Ford V6's, and still likes to tinker now & again. He made a big difference to the way Austin was running at last year's MOT time. And the fuel consumption figures improved a lot as well.
HTH
Best get timing & mixture set up properly at your local friendly tuners.
Geoff, the boss at my local MOT place used to fettle the Ford V6's, and still likes to tinker now & again. He made a big difference to the way Austin was running at last year's MOT time. And the fuel consumption figures improved a lot as well.
HTH
Top Gear TVR said:
I gave in today having swapped all the plugs, pulled every connector / plug apart, cleaned up the dizzy, tightened up the vac pipes, remade every earth strap etc etc.
I have settled for retarding the ignition 4 degrees at the 'octane' plug. I figure with a load of S-perts around me for the next few days - it'll be an easy fix for one of em?
what do you recon?
Hi Steve,I have settled for retarding the ignition 4 degrees at the 'octane' plug. I figure with a load of S-perts around me for the next few days - it'll be an easy fix for one of em?
what do you recon?
before Mat Smith got his hands on mine it ran terribly: I got a lot of heel-an-toeing practice keeping the thing from stalling every time the revs dropped with the clutch in. I have no idea what the did but it runs brilliantly now; starts on the 1st crank from cold.
Granted I am now biased towards him but you could do a lot worse than give him a bell-he might be able to sort it while you wait if you explain about the Tour.
Mat Smith Sportscars Unit 1E, Sovereign Way, Trafalgar Industrial Estate, Downham Market, Norfolk, PE38 9SW. Mobile 07526907434
HTH
Jeremy
Top Gear TVR said:
TreVoR is booked in here http://www.enginetuning.net/
Also an excellent choice-not used them for TVR myself but they did a good job of diagnosing the heap of dog's doo-doo that was my Audi A3 Quattro. Never buy a 2nd hand Audi unless you hate having money
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