[Mk2] [Turbo] loss of boost

[neilchan1981]

Hi can anyone please help. I have recently bought an mr2 rev1 turbo which has had an uprated intercooler manual boost controller and hks fuel cut defender fitted. Everything was running fine untill yesterday when i seemed to loose boost. It has subsequently got worse today and it seems to pop under full boost and then i cant boost atall. is this fuel cut. I also noticed the cover from the stock bov seems to keep popping off have done temporary fix to this but has made no difference. pls help. It also has a decat fitted. I have also noticed that the boost guage in the dash will creep up when not on boost. But i have a aftermarket guage fitted and this does not move. very strange.

[neilchan1981]

Hi can anyone please help. I have recently bought an mr2 rev1 turbo which has had an uprated intercooler manual boost controller and hks fuel cut defender fitted. Everything was running fine untill yesterday when i seemed to loose boost. It has subsequently got worse today and it seems to pop under full boost and then i cant boost atall. is this fuel cut. I also noticed the cover from the stock bov seems to keep popping off have done temporary fix to this but has made no difference. pls help. It also has a decat fitted. I have also noticed that the boost guage in the dash will creep up when not on boost. But i have a aftermarket guage fitted and this does not move. very strange.

I have had a little play and set the fuel cut to 12 and backed the boost off. It is slightly better but still stutters under load starting to think might be coil or rotor arm? any suggestions

[raptor95GTS]

i'd be checking the pipework for the extra boost gauge to find out what the car is actually running boost wise. The in dash boost gauge is in terms of what is reads fairly accurate (the top big mark is 10psi) however it's slower than a week in jail at moving so not good for looking for boost issues.

The rev1/2 are pretty sensitive to the BOV venting to atmosphere so if you have a leak there the car might have some issues under boost. Have you check for error codes?

[neilchan1981]

Hi can anyone please help. I have recently bought an mr2 rev1 turbo which has had an uprated intercooler manual boost controller and hks fuel cut defender fitted. Everything was running fine untill yesterday when i seemed to loose boost. It has subsequently got worse today and it seems to pop under full boost and then i cant boost atall. is this fuel cut. I also noticed the cover from the stock bov seems to keep popping off have done temporary fix to this but has made no difference. pls help. It also has a decat fitted. I have also noticed that the boost guage in the dash will creep up when not on boost. But i have a aftermarket guage fitted and this does not move. very strange.

Will check for error codes shortly. Now i have turned down the boost the after market boost guage is reading about 8psi. cant see anything obviouse with pipework but will get it smoked checked on tuesday.

[neilchan1981]

Hi can anyone please help. I have recently bought an mr2 rev1 turbo which has had an uprated intercooler manual boost controller and hks fuel cut defender fitted. Everything was running fine untill yesterday when i seemed to loose boost. It has subsequently got worse today and it seems to pop under full boost and then i cant boost atall. is this fuel cut. I also noticed the cover from the stock bov seems to keep popping off have done temporary fix to this but has made no difference. pls help. It also has a decat fitted. I have also noticed that the boost guage in the dash will creep up when not on boost. But i have a aftermarket guage fitted and this does not move. very strange.

Will check for error codes shortly. Now i have turned down the boost the after market boost guage is reading about 8psi. cant see anything obviouse with pipework but will get it smoked checked on tuesday.

Have checked for error codes and im getting 34 and 35. Excessive turbo pressure and open circuit for pressure sensor circuit. The hks fuel cut defender is wired to map sensor could this be the problem

[neilchan1981]

Hi can anyone please help. I have recently bought an mr2 rev1 turbo which has had an uprated intercooler manual boost controller and hks fuel cut defender fitted. Everything was running fine untill yesterday when i seemed to loose boost. It has subsequently got worse today and it seems to pop under full boost and then i cant boost atall. is this fuel cut. I also noticed the cover from the stock bov seems to keep popping off have done temporary fix to this but has made no difference. pls help. It also has a decat fitted. I have also noticed that the boost guage in the dash will creep up when not on boost. But i have a aftermarket guage fitted and this does not move. very strange.

Will check for error codes shortly. Now i have turned down the boost the after market boost gauge is reading about 8psi. cant see anything obviouse with pipework but will get it smoked checked on tuesday.

Have checked for error codes and im getting 34 and 35. Excessive turbo pressure and open circuit for pressure sensor circuit. The hks fuel cut defender is wired to map sensor could this be the problem

I have also noticed that if ignition is on and engine not running the boost gauge on the dashboard is on maximum. Any help would be appreciated.

[neilchan1981]

Hi can anyone please help. I have recently bought an mr2 rev1 turbo which has had an uprated intercooler manual boost controller and hks fuel cut defender fitted. Everything was running fine untill yesterday when i seemed to loose boost. It has subsequently got worse today and it seems to pop under full boost and then i cant boost atall. is this fuel cut. I also noticed the cover from the stock bov seems to keep popping off have done temporary fix to this but has made no difference. pls help. It also has a decat fitted. I have also noticed that the boost guage in the dash will creep up when not on boost. But i have a aftermarket guage fitted and this does not move. very strange.

Will check for error codes shortly. Now i have turned down the boost the after market boost guage is reading about 8psi. cant see anything obviouse with pipework but will get it smoked checked on tuesday.

Have checked for error codes and im getting 34 and 35. Excessive turbo pressure and open circuit for pressure sensor circuit. The hks fuel cut defender is wired to map sensor could this be the problem

Have disconnected fuel cut defender and rewired map sensor as stock. boost gauge is now normal but still have missfire under load

[neilchan1981]

Will check for error codes shortly. Now i have turned down the boost the after market boost gauge is reading about 8psi. cant see anything obviouse with pipework but will get it smoked checked on tuesday.

Have checked for error codes and im getting 34 and 35. Excessive turbo pressure and open circuit for pressure sensor circuit. The hks fuel cut defender is wired to map sensor could this be the problem

I have also noticed that if ignition is on and engine not running the boost gauge on the dashboard is on maximum. Any help would be appreciated.

Have done compression test and all cylinders are good. 170-180 across the board. Out of interest i rewired hks fcd and straight away as I turned ignition on the stock boost gauge whent straight up to maximum. Does anyone know a way of testing the map sensor?.

[raptor95GTS]

sounds like the FCD is goosed since the stock gauge does what it should do when the FCD isn't wired in

[neilchan1981]

Was thinking the same thing although im still getting a miss under load and a complete loss of poer sometimes which makes me think its the map sensor any thoughts?

[raptor95GTS]

map sensor on a rev1/2 only provides fuel cut and the in dash boost gauge, it has nothing to do with controlling boost levels or ignition

[mrturbotom]

Spark plugs, distribution cap and arm I'd replace if unknown age possibly leads too.
Check afm plug connection

[neilchan1981]

Even with fdc disconnected im still getting a lean missfire under load and complete loss of power like a fuel cut. And when fcd is connected stock boost gauge goes to max with ignition on with engine off. I am getting 2.5volt signal with no vacuum and it drops to 1.3volts with about a 1 bar vacuum. Do you know what the values should be? fault codes are saying open circuit in boost pressure sensor circuit. Any help would appreciated as im starting to pull my hair out lol

[neilchan1981]

I have ordered dizzy arm and leads as a precaution. Would a faulty arm cause fuel cut like symptoms?

[Peter Gidden]

fault codes are saying open circuit in boost pressure sensor circuit.

Well there's your answer!

And running multiple threads does not get more responses!

[neilchan1981]

sorry about that new to this lark wasnt shore i was doing doing it correctly

[neilchan1981]

sorry about that new to this lark wasnt shore i was doing doing it correctly

Ok I have replaced dizzy arm and leads and missfire is cured yay. Also cured fcd fault must of been dodgy connection as I have soldered all connections and its spot on. Thanx for everyones input

[raptor95GTS]

glad you've got it running