Idling high, 1100-1200 rpm Options

[6gsillyca]

Alright, so after finally getting a bunch of piping back from powdercoating, I was able to put everything back together, and start it up for the first time since putting it away for the winter last season.

Things I did during the winter:

swapped out the 540's for stock 440's
swapped out "possible chipped" JDM 93 ECU for 91/92 USDM ECU (both for SW20)
new plugs, ign wires, coil wire, cap, rotor
powdercoated valve cover, new VC gasket
powdercoated TB bracket, everything up until IM was removed
new (rebuilt) HO alt (120+ AMP)
new pass cv axle
deleted metal "plate" that runs behind fuel rail with vac line for FPR. Now running vac line routed behind engine, tucked along firewall.
throttle cable is NOT adjusted properly, since I can't get it to idle properly

I started the car up and it runs, but very rough. It will almost die, then shoot up to ~2k, then cycle back down to >400rpm, and almost die again. Goes through this cycle, and each cycle is maybe 10 sec long. Exhaust is not overly fuel rich (not much carbon splatter either), but it is spitting liquid. I don't know what it is, but it is very watery, no gasoline smell, and is a light black color.


Another thing I did notice with the new (91/92 USDM MR2 ECU) is that I now have a CEL. I was not able to get it to light up with my old JDM ECU. I was also able to pull 2 codes. 21 and 51.

Will look into the CEL codes, but it was running good when she went away last year...




EDIT:
Got it to idle good now. Turned out to be a missing FR insualtor, giving me a big air leak. Fixed it up now and it idles good, but high. 1100-1200. Any idea's?

This post has been edited by 6gsillyca: Jun 5, 2008 - 3:30 PM

[TRDGT4]

i just looked into your codes in my JDM repair manual and code 21 is to do with the Oxygen Sensor signal and code 51 is Switch condition signal but then again you do have a usdm ecu so maybe they are different good luck solving this oh and check for vaccum leaks could be that easy

[lagos]

You have a big vac leak somewhere after your afm.
From what i remember code 51 is a bs code that pops up when you rev the car in diagnostic mode. Not a real code to worry about. As for 21, you forgot to plug your o2 sensor back in.

[6gsillyca]

I looked into them aswell and got the same reasons, o2 sensor and switching valve, most likely ac idle up. These codes, AFAIK, are "monitored" codes, and should not affect how the engine runs (as far as my situation is concerned).

bad o2 will give me bad mpg, but shouldn't affect my idle that much (idle = closed loop = no o2 sensor input), and AC idle up, shouldn't affect my idle if my AC is not running. My o2 sensor IS plugged in, but I have a new one ordered.

However I did find a big boost leak and a missing vac line last night. Boost leak is either between TB > TB bracket, or TB bracket > TB inlet, as I had both the inlet and bracket powdercoated, so I will make a gasket for both and see if that helps. My missing vac line was the one that runs from the TB to the nipple on the valve cover. I forgot to reinstall it after I redid my valve cover.


What are the 2 nipples on the TB for? The front one looks like it runs to the EGR/charcoal canister, but the 2nd one is capped. What would it have been for.

This post has been edited by 6gsillyca: May 29, 2008 - 10:58 AM

[lagos]

bad o2 will give me bad mpg, but shouldn't affect my idle that much (idle = closed loop = no o2 sensor input)

You have that backwards. Bad o2 will affect your idle. Idle = closed loop = o2 sensor input

[6gsillyca]

Why is that. Shouldn't closed loop mean no sensor input? If it is idle then the ECU should be able to run the engine off stored maps.

Either way, I do have a replacement sensor on its way. I find it odd how the o2 sensor was good last year but bad now. I think it may have been faulty before I took out it anyway, but with my jdm ECU I didn't have a CEL, and now that I do, it is able to give me a code.

I think my problems are more vac/air leaks rather than bad o2. I know you said o2 affects idle, but I think it is mainly because of someting more major.

This post has been edited by 6gsillyca: May 30, 2008 - 11:13 AM

[lagos]

Why is that. Shouldn't closed loop mean no sensor input? If it is idle then the ECU should be able to run the engine off stored maps.

No, like I said, you have it backwards. Closed loop means the ecu is running off the o2 sensor. This happens at idle and cruise only. When you floor it, the ecu uses stored fuel maps and ignores the o2.

Either way, I do have a replacement sensor on its way. I find it odd how the o2 sensor was good last year but bad now. I think it may have been faulty before I took out it anyway, but with my jdm ECU I didn't have a CEL, and now that I do, it is able to give me a code.

Unless you forgot to plug it in, I really doubt your o2 just went bad for no reason. You probably bought an ecu from another year car, that has the o2 inputs on different pins.

Why did you take out that ecu in the first place? Was it giving your problems?

[lagos]

swapped out "possible chipped" JDM 93 ECU for 91/92 USDM ECU (both for SW20)

This is your problem. You cant use a 91 ecu on your 93 motor.

[6gsillyca]

I swapped the ECU out because I swapped out the 540's, in an attempt to reclaim some mileage, for the stock 440's.

From previous discussions with Jay, it appeared that the stock jdm ECU may have been chipped, as a stock gen2 ecu shouldn't run 540's properly. I got a stock ECU to run the 440's properly, and from the bit of research I did on mr2oc I thought that a 92 ECU would have worked.

As I had mentioned, the o2 sensor may have been bad from before, but because my 93 jdm ECU doesn't give me a CEL for some reason, it may have not been apparent to me. When I plugged in the 91/92 ECU I was able to pull codes again.

[6gsillyca]

Alright so I guess one of the FR to head insualtors fell off the FR when I was re-installing it, giving me a huge air leak from my fuel rail. Put my old insulator back on (have a fresh set of all FR/injector o-rings coming from toyota) and it fired up perfect!

Now I just need to figure out why i'm idling so high. I'm at 1100-1200rpm. Its not the throttle cable either, because it had a bit of slack in it, and was still idling high.