Injector type & rolling road / ECU remapping thoughts
Discussion
Well hello there.
After some pretty serious self diagnostics the S3 is still lacking power. I've checked compression, fuel pressure, sensors (MAP, Lambda, TP etc) set the tappits, new plugs, leads etc etc. I think I've pretty much exhausted everything other than the injectors or ECU MAP problems.
Firstly, does anyone know what the injectors model should be? They seem to be color coded, the ones on the car seem to be yellow (ring) & I also have a spare set someone has given me which are orange.
Secondly, I have been considering taking it to Austec as they seem to be the real experts, but although the rolling road test is reasonable, If it needs re-mapping which I'm sure it does, I guess it's going to be seriously expensive. Any thoughts????
Thanks,
Rob.
After some pretty serious self diagnostics the S3 is still lacking power. I've checked compression, fuel pressure, sensors (MAP, Lambda, TP etc) set the tappits, new plugs, leads etc etc. I think I've pretty much exhausted everything other than the injectors or ECU MAP problems.
Firstly, does anyone know what the injectors model should be? They seem to be color coded, the ones on the car seem to be yellow (ring) & I also have a spare set someone has given me which are orange.
Secondly, I have been considering taking it to Austec as they seem to be the real experts, but although the rolling road test is reasonable, If it needs re-mapping which I'm sure it does, I guess it's going to be seriously expensive. Any thoughts????
Thanks,
Rob.
Something's obviously very wrong. Back to basics then, what is the air/fuel ratio like, what ignition timing have you got, what CR have you got? If that doesn't reveal an obvious problem then look at manifold depression and exhaust backpressure under power, check how much valve lift you're getting per valve, check the cam timing, etc.
Hi, thanks for your feedback.
Compression was good on all cylinders, ignition timing about 10deg static & reached about 36deg at 4000rpm. Not sure what CR is???
Generally running very rich, pretty high CO & you can really smell the fuel in the exhaust.
When I did the tappits & checked the valve lift & it seems to tie in with a figure I found under the ford scorpio website at about 6.5mm.My local guarage put a meter on the vacuum pipe to the MAP sensor & indicated the vacuum was OK, although I'm not 100% on that. How do I check such things as exhaust back pressure & cam timing etc???
Many thanks,
Rob
Compression was good on all cylinders, ignition timing about 10deg static & reached about 36deg at 4000rpm. Not sure what CR is???
Generally running very rich, pretty high CO & you can really smell the fuel in the exhaust.
When I did the tappits & checked the valve lift & it seems to tie in with a figure I found under the ford scorpio website at about 6.5mm.My local guarage put a meter on the vacuum pipe to the MAP sensor & indicated the vacuum was OK, although I'm not 100% on that. How do I check such things as exhaust back pressure & cam timing etc???
Many thanks,
Rob
The shape of the torque curve can give you a lot of clues about the nature of the problem. Do you have a torque curve? Do you have a plot from a healthy engine to compare it to?
Looking for specific faults:
Check the manifold depression with the engine running at three quarter revs and full throttle, it shouldn't be more than about 1 psi. Exhaust back pressure can be measured by plumbing a pressure in to one of the lambda sensor holes. On the cam, I mean check the lift on every valve not just a sample, it may be you have got a worn lobe. Cam timing is tricky to check so check the other things first, but go back to this if nothing else shows a problem. The fact that it is running very very rich already suggests that you do have other problems.
Looking for specific faults:
Check the manifold depression with the engine running at three quarter revs and full throttle, it shouldn't be more than about 1 psi. Exhaust back pressure can be measured by plumbing a pressure in to one of the lambda sensor holes. On the cam, I mean check the lift on every valve not just a sample, it may be you have got a worn lobe. Cam timing is tricky to check so check the other things first, but go back to this if nothing else shows a problem. The fact that it is running very very rich already suggests that you do have other problems.
Allo Allo.
Well, this week I got hold od a 'try or buy' replacement ECU & it didn't make any difference to the performance, at least it's a major thing ruled out though.
Also convinced it's not an exhaust problem, no problem with the flow & a little louder now if you know what I mean!
Also replaced the fuel filter today.
Haven't managed to get hold of a vacuum gauge to check manifold pressure, but seems to suck OK with just a finger test!
Sooooooo. What's next? Hmm, well, I'm going to try checking the fuel pressure in more detail this week. Does anyone know what it should be & how this changes with revs?
After that, I'm going to take off them plenum chamber & switch over the injectors with this spare set I have been given.
If this doesn't help then I guess I'm going to have to check the cam timing, but that's not a job to look forward to!
Well, that's the plan, any more suggestions would be greatly appreciated.
Rob
Well, this week I got hold od a 'try or buy' replacement ECU & it didn't make any difference to the performance, at least it's a major thing ruled out though.
Also convinced it's not an exhaust problem, no problem with the flow & a little louder now if you know what I mean!
Also replaced the fuel filter today.
Haven't managed to get hold of a vacuum gauge to check manifold pressure, but seems to suck OK with just a finger test!
Sooooooo. What's next? Hmm, well, I'm going to try checking the fuel pressure in more detail this week. Does anyone know what it should be & how this changes with revs?
After that, I'm going to take off them plenum chamber & switch over the injectors with this spare set I have been given.
If this doesn't help then I guess I'm going to have to check the cam timing, but that's not a job to look forward to!
Well, that's the plan, any more suggestions would be greatly appreciated.
Rob
Simple stuff from me....Air Filter 
, blocked crank case breather , coil/weak spark , collapsed exhaust baffle .
My favourite guess is.......... inlet hoses collapsing, check the inside of these they are double skinned and the inner skin can bellow out under vacuum strangling the air flow.
, blocked crank case breather , coil/weak spark , collapsed exhaust baffle . My favourite guess is.......... inlet hoses collapsing, check the inside of these they are double skinned and the inner skin can bellow out under vacuum strangling the air flow.
robculm said:
Haven't managed to get hold of a vacuum gauge to check manifold pressure, but seems to suck OK with just a finger test!
That's not what I was talking about at all. Check the manifold depression under power, this will pick up a whole range of problems caused by faults on the induction side. Check the exhaust back pressure under power, this will pick up problems on the exhaust side. Those two simple checks can let you work out whether the problem is internal or external.
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