[Awesome-X]

Alright, I went and traded my Camaro for an MR-2 tonight with a turbo, I don't know much about it because he had just received the car himself. It runs great, and I absolutely love it, it has t-tops, too which my Camaro also had. He said that it runs lean sometimes, and gave me an AEM F/IC fuel/ignition controller with the car which hasn't been installed yet. It has a fuel/air mixture ratio gauge in the car and in colder denser air the car seems to run quite a bit lean and it'll die.

My question is how can I solve this? And how can I hook this fuel tuner up? I'm mostly a small block chevy guy but I'm absolutely in love with this new car, so any help or suggestions would be greatly appreciated!

 

[MR2Jedi]

Does it have the stock turbo?
In stock form, in good condition, there's no way the stock CT26 turbo can outrun the stock fuel system. Toyota designed them to run alittle rich.
I wouldn't even mess with the A/F ratio without a dyno.
What makes you think it's running lean?
Need more info. Maybe a pic of the engine bay.

Oh, Welcome to the forum!

 

[Awesome-X]

Alright I had a look at it and it is a stock motor and turbo, I have an A/F ratio gauge that reads lean when it won't idle and reads stoic when it idles perfectly, so I'm not real sure what could be causing it.

 

[MR2Jedi]

Alright I had a look at it and it is a stock motor and turbo, I have an A/F ratio gauge that reads lean when it won't idle and reads stoic when it idles perfectly, so I'm not real sure what could be causing it.

Low fuel pressure.
Partially clogged fuel filter or line.
Clogged injectors.
Leaky vacuum sensor hose to FPR.
Come to mind off the top of my head.

Good lookin 2 , BTW.

 

[Awesome-X]

Where is the FPR? My father in law (whos a mechanic, and not just of chevy's :lol made a comment earlier when he saw the motor that there was a vacuum line missing off of what he believed to be the FPR. It has an aftermarket gauge on the side of it and is definitely missing a vacuum hose.

 

[MR2Jedi]

Where is the FPR? My father in law (whos a mechanic, and not just of chevy's :lol made a comment earlier when he saw the motor that there was a vacuum line missing off of what he believed to be the FPR. It has an aftermarket gauge on the side of it and is definitely missing a vacuum hose.

On fuel rail, just above the intake runners. FPR is on the driverside between intake runners and valve cover.
If thats the case, there should be a line from FPR to fuel rail and at the other end of rail, there is another line to intake manifold.

 

[Awesome-X]

Alright, I'll have a look soon to see if I can sort that out.

While I was at it I had a look at the O2 sensor, its a 4 wire sensor, and has been cut and is spliced into 2 wires. Anyone know why someone might do that?

 

[MR2Jedi]

Alright, I'll have a look soon to see if I can sort that out.

While I was at it I had a look at the O2 sensor, its a 4 wire sensor, and has been cut and is spliced into 2 wires. Anyone know why someone might do that?

Probably to install that A/F Ratio gauge.

 

[Awesome-X]

Well let me rephrase that. The original harness plug has been completely cut off and its now only wired into 2 wires. One is a hot wire, and I'm not sure where the other one goes yet. Are these supposed to have stock 4 wire O2 sensors, or is it a 2 plug stock?

 

[MR2Jedi]

Well let me rephrase that. The original harness plug has been completely cut off and its now only wired into 2 wires. One is a hot wire, and I'm not sure where the other one goes yet. Are these supposed to have stock 4 wire O2 sensors, or is it a 2 plug stock?

Stock is 4 wires. I had to rewire mine last year

 

[Awesome-X]

-.- great. I guess I'll need to find a wiring diagram then, that could also be part of my problem.

Also my speedo doesn't work. Would that be cable driven or VSS?

 

[Awesome-X]

Ok, well I finally took some pictures of my wiring stuff and a couple other things.

First things first. I need to know where to hook my O2 sensor up at. Right now it's just hooked into a power wire then runs to the A/F ratio gauge in the car. Where is it supposed to go?

And second I have this huge cluster of wires and I have no idea where they go. They come out the passenger side from the front of the car. So if someone would go outside and check their wiring harness for me I'd appreciate it.

Here is a vacuum port coming off my intake and going nowhere. Is that supposed to go to my FPR by any chance?

This goes to my boost gauge. I don't know why it is where it is. It goes into a T which then goes into my intake. Where should my boost gauge be tied into?

And last is my FPR. There is a nipple at the end of it that I'm assuming a vacuum hose should go to, but there isn't one. Where should this be coming from?

 

[ModifierMR]

FPR is your Fuel pressure Regulator, The factory version is located on your fuel rail at one end. and has a vacuum line going into it. It appears you have an aftermarket FPR. My question is why? On a stock car why? I would simplify your life and remove it for right now and try and return the fuel system to stock.

That wiring harness does not appear to be stock. I would trace and and fight where it goes. It may go to an old aftermarket alarm which is common in older MR2's.

The 02 sensor wire from the factory should be located on the engine harness right around where o2 sensor is on the exhaust manifold. It should be 1 wire. If you have an aftermarket wideband o2 sensor for your gauge..you will have to replace it with an OEM version when you hood it back up to the factory harness.


All in all, I would remove all the needless aftermarket junk (the FPR, A/F gauge, and all) and put it back to stock. The engine works great and produces good power in stock form... half assing it and having these things on your motor is pointless. If you had a big turbo upgrade, or aftermarket ECU, or something that required a new FPR then it would be one thing.



The factory boost gauge reads from the boost sensor located on the rear fire wall on the passenger side near the intake manifold. If your aftermarket boost gauge is hooked anywhere but here, I would suggest moving it.

Here are some pictures of the STOCK 3SGTE engine bay.

 

[Russell D]

^^ I agree, you don't need an aftermarket FPR, I'm guessing that your car was owned by some ricer, because when I was in my ricer days I put all that same junk(aftermarket FPR and useless narrowband A/F gauge) on an old civic I had, which we dyno at 53whp!!!

Anyway back on topic, you mentioned the speedometer earlier, the 91/92 mr2's are cable driven and commonly break, my front one was broke when I bought my mr2; the 93+ mr2 are electronic and I have no clue what would be wrong if yours is a 93+

With the wiring for the O2 sensor, is the factory plug still there is has that been cut off? If the plug is still there I'd replace the whole O2 sensor. This is a good place with a lot of mr2 parts: http://www.twosrus.com/catalog/index.php?cPath=22_31&osCsid=16987764e5853b81cbab459fb9f6990f

Next I would remove the Fuel Pressure Regulator and put on a stock one.

My guess is that replacing both of those will most likely fix your iddling issue, because both of those could be or are affecting the A/F ratio.