Toyota Celica Supra Forum banner

1 - 8 of 8 Posts

·
BIG BOSS HOSS
Joined
·
4,460 Posts
Discussion Starter #1
That's 2jzgte. :) I need help to trouble shoot this thing. It's got a date with the body shop on 5/31 and I need it run/move properly for the bodyshop folks.

Just a bit of background, MAF delete(no idead how that works), single turbo, non stock 550s and a SAFC2. It ran great in the previous owners car but in my Mk3 and now Mk2 it's rich.

Symptoms: Low RPM missing with black smoke at the slightest throttle or load up to about 50%. WOT is fine all the way to 7K RPMs. I'm not sure where to begin these engines are totally foreign to me. I was thinking bad map sensor or even ECU.. There are no vacuum leaks.

Thanks!
 

·
Super Moderator
Joined
·
8,160 Posts
Did you check the ignition coils for cracks? Pretty common on 2JZ coils. Also I presume you are running a tighter gap than stock?
 

·
Registered
Joined
·
15,004 Posts
Have you checked the engine codes? for the MAF delete, is it a usdm motor? if so, would have the be an HKS VPC, or maybe an e-manage to eliminate the maf. Might be a jdm, they never had a maf.
 

·
Registered
Joined
·
491 Posts
Check your fuel pressure regulator, some times the diaphram will rupture and add lots of extra fuel.
(Edit to elaborate) The vacuum / boost reference line controls a diaphragm that in turn controls fuel pressure. As they age, the diaphragm can become crispy and then rupture. This will cause fuel pressure to flow into the vacuum line and add raw fuel into the mix. This is especially noted at low to idle, it can also cause misfire conditions on one or more cylinders depending on the location of where the un-atomized fuel is added to the intake plenum.

Check the fuel pressure regardless, make sure its at the correct range for the vacuum / boost condition. If its out of range; check the regulator to confirm its good. Also search for a pinched or obstructed return fuel line; the return line should have almost no resistance, to check be sure your fuel cap is removed because your fuel system is a semi sealed unit because of emissions regulations. Some tank atmosphere is vended at the charcoal canister, but this small venting is just too little to prove or disprove a return line blockage.

Check the TPS to make sure its in spec, they can be a little temporamental on occasion.

Check the MAP sensor wiring to be sure its not damaged; also confirm MAP sensor is good. ( not totally familiar with MAP based toyota systems, but on Honda's if the MAP is damaged or the connection is poor the motor will run very badly.
 

·
BIG BOSS HOSS
Joined
·
4,460 Posts
Discussion Starter #5
Thanks for the replies. I managed to lean it some with fiddling with the SAFC for the body shop. Drove it 10 miles home with no issues, still rich but drive-able on 114 race gas..

I did some digging William, and the engine was from a '94 JDM Supra hence, no MAF.

SliverMk2, no coil pack cracks.

Klause, the 550cc injectors with my 1:1 FPR recommends 43.5psi and that's where it's set. When I get some time, the codes will get checked. Probably the MAP or even the ECU knowing my luck!
 

·
Registered
Joined
·
15,004 Posts
Yeah, could be the map. Do you have a mechanical boost/vacuum gauge? The SAFC should interupt the map signal, so the AFC should give a vacuum reading, and you can compare it to your mechanical gauge to see if it is reading correctly. Aside from that, you'd have to check the signal voltage at idle and follow the spec range in the TSRM to determine if it is reporting correctly or not. If it is, then I would suspect a vacuum leak.
 

·
BIG BOSS HOSS
Joined
·
4,460 Posts
Discussion Starter #7
Yeah, could be the map. Do you have a mechanical boost/vacuum gauge? The SAFC should interupt the map signal, so the AFC should give a vacuum reading, and you can compare it to your mechanical gauge to see if it is reading correctly. Aside from that, you'd have to check the signal voltage at idle and follow the spec range in the TSRM to determine if it is reporting correctly or not. If it is, then I would suspect a vacuum leak.
Yea, have a Greddy vac/boost gauge and am getting 21 inches of vac at idle. One thing you should know about the 1/2jz, they are extremely tolerant of vacuum leaks. They are nothing like a 7mgte. I can drive around with the intake IC pipe off! If you see 1st time starts with those engines, most don't have any IC piping but start and run just fine.
 

·
Registered
Joined
·
15,004 Posts
Thats because it is a map based system. It goes off of the intake manifold vacuum/boost, which wont cause any problems if an i/c pipe is off other than it wont boost. By vac leak, I meant on the actual intake manifold itself, like one of the vac lines is cracked/split, maybe even off.
 
1 - 8 of 8 Posts
Top