tcd1388

Hello, I am hoping someone out there can help with my problem. My Mustang GT has 19000 miles, a pro charger, and axle back exhausts. custom tuner, been running fine till one day, backed it out, and started running rough, misfiring. took it to a specialist at ford, and he has had it for several weeks and cannot find the problem. He has done a battery of checks, and has determined the 5-8 bank has compression low, all checks indicate no internal mechanical issues (piston) problems etc. He is suspicious that the cam timing is off on the vvt.
He has replaced the intake cam phaser on that bank, and did not cure the problem. Has anyone else had similar problems, or is this a freak problem. My Ford tech is baffled, and ready to give me back the car not running. any help would be appreciated, thanks

kirk35

Do you have the actual results of the compression test? Did they perform a leak-down test? My first guess without any additional information would be that you lifted the head, but I would like to see the compression test results.

How much boost are you running? Stock head bolts?

jz78817

Not to be a jerk (which means I'm about to be a jerk) but you put a supercharger and tune on an engine which wasn't designed for it. Which means you've voided your powertrain warranty. If you have lifted the head like kirk35 suspects, the repairs are coming out of your pocket.

P51C

If you have compression low multiple cylinders it's not a cam phaser issue, that's bull****. The cylinders are all at different places in the firing order so, for multiples to be low it has to be something they all share in common, all the time, like a head gasket.

There is nothing wrong with the factory bolts and gaskets in a low boost application. This engine WAS designed around a low pressure supercharger. Roush slaps TVS blowers on non-modified Coyotes all the time, with full warranty. It was well-understood by the engineers who designed the Coyote that 5 seconds after release, there would be a blower kit available for the car and they built some headroom into the design for that.

scottmach

Absolutely spot on.

jz78817

You know this how?

And even if they did, Ford still has grounds to void your warranty if your engine has damage which can reasonably be explained by a third party add-on.

P51C

Read a little on the history of coyote development, it's all there. No one is saying they don't have the right to stick it to him but , the claim no one daw this potential on the design isn't true.