JaySc300

Hi. I purchased a 92 SC300 with a bad head gasket. It had hesitaion issues and unstable idle when cold. I attributed these issues to the bad head gasket. I replaced the engine with a jdm one and replaced fuel filter, cap, rotor, plugs, and plug wires. The hesiation issue is present and now the engine wants to idle at 1800 rpms. I used all sensors and the manifolds from the USDM engine. The mechanical timing is exact however when in timing mode im at 18 or 20deg with distributor full retarded. After cleaning the IACV , the high idle began and i cannot set timing. The engine is sputtering and lopes. The acceleration issue was fixed when I fully advanced the tps. It would hesitate badly unless advanced fully. Im ordering a TPS and IACV. would these fix the sputtering or is some other culprit ie coil, maf, fuel pump, ecu. I checked codes and none present for engine or transmission. No smoke from the exhaust either. Any help would be appreciated. Thanks

topdog849

iTrader: (1)

you probably dont need a new tps you just need to set the one you have properly, ive posted the alldata procedure on the forum search for it. try diconnecting the battery for 10 mins so the computer will try to relearn its idle. also use a big bottle of lucus fuel system cleaner in your gas tank. but if you do end up replacing it i believe theres a camery with the same part number for tps and only costs 12$ compared to 100 bucks at advance auto. regardless do a search

JaySc300

Thanks. Yeah I just got the code for lean. I did the FSM procedure to determine if its the O2 sensor or Injector and no code for those. Its prob cause the tps is maxed fully. My meter took a crap so Ill buy a new one and set it. I was just advancing it a hair resetting ecu and driving around for a day or two to see if it stalled. I kept doing that and it finally ran with the tps maxed but now its lean. Thanks Ill set it per factory.

JaySc300

Okay set the TPS per FSM and reset ECU. Hesiation and stallling when shifting from park to any other gear kills the engine. And idle remains at 1800 rpms.

topdog849

iTrader: (1)

your egr may be stuck open, try disconnecting the vacuum line to the egr and pinch it off. or replace it. also try bypassing your fuel pump ecu by putting a jumper wire on terminals B+ and Fp under the hood on the diagnostic port

ConSynX

iTrader: (1)

Having a high idle start AFTER cleaning the IAC makes me think it didn't work. I had a hesitation that went away with a new fuel pump, but your lean sounds like a lack of air making it to the cylinder.

JaySc300

Okay Ill check the EGR. I already did the Fuel Pump ECU bypass. Per the manual pins 4 to 6 has 40 ohms and factory says 20-30 on the IACV. Dont know if thats grounds on replacing the sensor.

Ali SC3

iTrader: (10)

Jdm engine uses a map sensor right. vac leak usually shows up as a high idle. make sure everything is routed correctly.. especially because the jdm engine doesn't have egr and if you used the USDM manifold you probably still have all your egr hoses going places. I hope that made sense.

JaySc300

The jdm engine is a bone stock jzge. It came minus manifolds. Im using all manifolds and sensors as well as the MAF from my car. Hence, since its acting the same as the old mocha-oil engine, I think its sensor, spark, or fuel related. Ive checked all vacuum hoses. The only thing remaining from on the JDM motor that I didint swap is the PCV valve.

Ali SC3

iTrader: (10)

I don't think you understand. unless you used the USDM head on the JDM block, there is no way you can have a functioning egr. the port for the egr is on the head, and the JDM head does not have it.

you are right if you use all the usdm electronics, yes you can retain the maf sensor setup, but the egr has to go unless you used the usdm head.

JaySc300

If your talking about the port at the back of the head, the engine had it. I swapped over the EGR passage cover at the rear of the head. I purchased my engine from Attarco engines in CA. The company is based in CA and the engine was sold as a CA approved engine. Since I have the CA model with the EGR temp sensor, I figured if it was EGR related the ECU wouldve thrown a code a while ago. So i must have classed the engine as a JDM when it was prob off of an American model. My bad.

JaySc300

If your talking about the port at the back of the head, the engine had it. I swapped over the EGR passage cover at the rear of the head. I purchased my engine from Attarco engines in CA. The company is based in CA and the engine was sold as a CA approved engine. Since I have the CA model with the EGR temp sensor, I figured if it was EGR related the ECU wouldve thrown a code a while ago. I called Attarco and confirmed their engines have the EGR ports.

Ali SC3

iTrader: (10)

yeah its probably a us model then, thats a good sign at least. if its not vac leak related its probably in the throttle body area (IACV or TPS as you said). Also make sure the breather hose on the passenger valve cover is connected properly to the intake tubing. same with the power steering idle up vac lines (the 2 lines going to the reservoir).

JaySc300

Okay thanks. Yeah the power steering vacuum lines and vc breather hose and intake pipe coupling are all new. I ordered a IACV yesterday. Hopefully Ill kill two birds with one stone. If not at least get my idle down so I can time it properly.

JaySc300

Okay as an update. I replaced the IACV and reset the ecu. Still high idle at around 1700. As the engine warms up it starts to drop down than it just creeps up to 1700 and stays there. It drops to 1000 rpms in drive and reverse. I removed the throttle body to double check everything. I plugged the EGR and reset ECM. I also replaced most vacuum lines with about 6 feet from Autozone. I'm stumped. It still has code 25 Lean at times especially when I turn on the AC on long drives. I guess Ill change the tps next since the car wont even run without stalling unless the tps is pretty much adjusted to its max setting. After each change I have reset the ecu. I did the diagnostic with the DC2 and only codes after test drive was the lean so far.