1jz wont boost/rev past 3k

[squish_m8]

Hey All,

I've got another problem with my supra (GA70 with a stock JZA70 1JZGTE). I have tried searching already but still not sure what the problem is.

So I took my car out to work this morning and when I tried to give it a bit of boost it would just not rev past 3000rpm and felt like a fuel cut or something after that. Although it is perfectly fine driving and changing below that. also when there is no load on the engine I can rev the 1j up to redline.

I'm fairly sure it has something to do with the airflow some where or a faulty sensor but I dont know where to start.

Another problem which I dont know if its related or not that happened in the last few days is the car has become noticeably louder but at first glance there does not seem to be any breaks in the exaust system. I'm thinking maybe blown cat?

any help would be apprieciated

Cheers, Kieran

[Maverick]

Could be a melted cat... doesn`t sound like it though I had a similar problem but it revved a bit harder than 3k. check all vaccum lines around the throttle body are on and tight. Also check your cooler piping hoseclamps are all nice and tight (it sounds like a blown off intercooler hose if the car is louder and not revving under load) if that all checks out it could be something ECU / ignition related but start simple

[squish_m8]

so i checked all piping and lines and all seemed to be fine apart from 1 small vac line which i blocked up. this only made it marginally better though.

also: NEW SYMPTOM: pours out black/grey smoke on boost... would this mean the turbos have gone?

[Maverick]

nah sounds ignition/fuel related... If a turbo has let go it should still rev, and it will be pouring white smoke.... check ecu (open it up and check the innards to see if anything has burst...) coil packs and leads... if you can, borrow some bits to swap to diagnose it... I would say it`s probably not something major though so don`t fret

[HAVABEER]

isn't limp mode 3000 revs?

actually i think its 2000 revs? i vote check ecu for error codes and then reset it

[JP]

Check the line to the map sensor then check the TPS

[japlish]

Nsw? .....

[squish_m8]

Okay, I chucked the problem on Facebook and a mate had a similar problem, turns out the MAP sensor was stuffed. Tried another and was good and would drive properly but still puff a bit of black smoke and no real improvement in noise. So I think i've got another problem going on there....
... but at least I can drive it now