Low Compression / Massive hidden vacuum leak
 

Hey guys, trying to diagnose my RX7. I downshifted to 4th and pushed maybe 7psi of boost when this happened. Car was running perfectly up until then. Has no trouble starting now but it clearly has something going on with it. Doesn’t smoke anything except for the standard rotary smoke. I initially Swapped out ignition coils with a used set I bought. Replaced spark plugs, and searched everywhere for a vacuum leak. I’ll replace the spark plugs wires next to rule those out but they tested okay on the multimeter. I’m not sure what a blown motor or blown turbo sounds like and I haven’t had a chance to compression check it yet. Little to no vacuum, dumping fuel, oil pressure seems okay. Pulls more vacuum when it’s revved. but if anyone else has dealt with this before and can offer their 2 cents I would greatly appreciate it! What does this sound like to you guys??
haltech 2000 ecu
borgwarner 9274
All other supporting mods for single turbo

Do you have a paper gasket on your lim, uim or throttle body?

metal gaskets for all, gaskets look to be in good shape aside from the lim, haven’t taken a look at that one

Check for that. It will be easy to see. You can put your hand over the end of the intake elbow while the car is idling and either it will stall or continue running.

if it continues to run then you are on the right path with a massive vacuum leak. Best case scenario, you have a paper lim gasket and a peice of it blew out. A lot more common than you think and an easy fix on a single turbo car. Wouldn't hurt to check the o ring between the throttle body and intake elbow as well.

Ruling out the possibility of a vacuum leak would be the first step. If everything checks out then you would move on to checking components

So remove the intercooler piping from the elbow and cover it on the open end? Havent heard of that test before so I’ll give it a shot. Appreciate the advice!

updates?

LIM has a metal gasket that looks to be intact and I’ve checked the throttle body o-ring as well. I’ve got the car so torn down that I haven’t been able to do any running tests on it since I swapped in the coils. At this point I’m waiting to compression test it and tear down the turbo to see what I can find. Curious to know if a cracked/broken apex seal would cause it to dump fuel or would it be the combination of the vacuum leak from a low compression symptom causing the ecu to dump fuel?

hmmmm..... if there was any internal damage you would have other symptoms, which you do not. at this point you're going to want to use the haltech. run through your sensors, signals and voltages and see if anything is wrong.