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I had my ECU tuned with the uprev software a few months ago and everything was perfect. Yesterday I had a Cosworth Plenum installed and the car would cut power at 4500 rpm like it was hitting the rev limiter. Reinstalled the original setup and problem gone. Def was not vaccum leaks or improper install.
I am just amazed that the Cosworth makes such a big difference that the tuned ECU can't adjust for it. I figured on an N/A vehicle the tune wouldn't be so offset by a plenum change?
Expert please give opinion, I will be taking it in for a tune but I have a track day tomorrow so I had to go back to original setup.
I recently installed the cosworth without retuning it but did not run into this issue.
Adam@z1 ran into a very similar issue where the gasket he used not creating a good seal, but looks like you checked that already. There isn't much else to check other then the barbed fittings and plugs to see if they are on securely with some sort of sealant, even so it wouldn't create such a dramatic loss of vacuum where you could not rev past 4500. Have you checked that stupid rubber gasket they make you put on the carbonfiber caps? Or even perhaps a crack there, might be easier to see from the inside of it?
I recently installed the cosworth without retuning it but did not run into this issue.
Adam@z1 ran into a very similar issue where the gasket he used not creating a good seal, but looks like you checked that already. There isn't much else to check other then the barbed fittings and plugs to see if they are on securely with some sort of sealant, even so it wouldn't create such a dramatic loss of vacuum where you could not rev past 4500. Have you checked that stupid rubber gasket they make you put on the carbonfiber caps? Or even perhaps a crack there, might be easier to see from the inside of it?
I will PM my tuner to see if he can double check. I think if it was a gasket problem would I not have issues at idle? So weird that it happens at upper RPM.
I will PM my tuner to see if he can double check. I think if it was a gasket problem would I not have issues at idle? So weird that it happens at upper RPM.
Higher revs, more vacuum pull, so no probably wouldn't notice it until higher revs. Especially if you just have a small leak.
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Correct, that at higher rpms is where the problem will manifest itself.
When I assembled the cosworth I was surprised how easily the gaskets on the cap can be easily mis-aligned and susceptible to pinching. I definitely would check that before the intake manifold gasket as that one is nearly impossible to install incorrectly. The other place would be the hose connections, but that is probably not it as your tuner tried your orig parts with success. Good luck.
Correct, that at higher rpms is where the problem will manifest itself.
When I assembled the cosworth I was surprised how easily the gaskets on the cap can be easily mis-aligned and susceptible to pinching. I definitely would check that before the intake manifold gasket as that one is nearly impossible to install incorrectly. The other place would be the hose connections, but that is probably not it as your tuner tried your orig parts with success. Good luck.
Thanks gabe, you are an awesome member of this site
A big thank you to everyone in this thread. I sent it to Cosworth after my installer found a leak following a pressure test. The manifold was sent back to Cosworth for inspection and they found it to be a bad casting and will be sending a replacement soon.
Cosworth Plenum on tuned ecu = problems
