Red top vs Black top ECU

[bulgartkd]

Hi Guys!My '95 S13 black top has been installed for about a month now, but still cannot figure what is wrong with the idle. The idle just goes up and down and wants to die if gas is not given. When driven, especially when cruising the car jerks and hesitates and you need to jump on the gas for it to go. It just doesnt feel like a turbo motor. Everything is JDM stock, including the i/c and exhaust, only upgrade is the fuel pump. We have checked the timing, the fuel delivery, changed the CAS, changed the MAF, check for vaccum leaks....nothing! The only thing we have not done is change the ECU. No one around us has a black top ECU, but a buddy has a red top, so I can borrow his. Are those interchangable? Any difference in performance/signal? Any suggestions? Thanks in advance!

Alek

[daz1320]

Ok heres the deal.I had the same problem.Well actually my car ran very well with a 62 ecu.Then one day it just started to idle all messed up.It would drop to about 500 and sometimes die.Also it had a bad studder/hesitation problem.So i checked everything that you said and the plugs and came up with nothing.I also pulled the code on the ecu and it said MAF.To make a long story short I regrouned the maf and it kind of fixed it.A few days later i got my e5 ecu in the mail,plugged it up and now it is almost totally normal...the idle still may go up to 1000 but it drops again....check your maf wires..try a e5

[bulgartkd]

E5 is black top and 62 is red top, correct? I have the correct ECU for my black top, but I was wondering if I could use the red top ECU to at least test drive and check if the problems may go away. Are they interchangable and if not, what are the differences? BTW, I also changed the spark plugs. The MAF was changed, also the CAS, problem still exist. We opened the valve cover, checked the timing and it is set to factory. I dont know what else to look for. I am sure it is something small, but very frustrating.....Thanks!

[SpeedRacer1]

Look to see if the ECU is throwing a code. I ran a blacktop E5 ECU on my redtop awhile back, it had a weird fuel hole that killed power for some reason. But then the ECU would reset itself like 2 min later and run fine. The only difference between the redtop and blacktop is the O2 sensor, so this may play a role. But people cross use ECU's all the time.

Another guess of mine would be TPS. But try the codes first, if it thows something just unplug it and plug it again. This has worked for me on multiple occasions.

[Pepperoni]

Have you tried adjusting the IACV (intake air control valve) or something like that? You know the main big entry for the throttle body, well there should be a smaller hose right next to it. Follow that hose and it should take you to this small box looking thing. I think it's between runner 3 and 4...Theres a green label that says air control valve or something similar (sorry i havent looked in a while). You can use a screwdriver to adjust the idle. It will definitely help. Also, what did you do with the hard line that goes to your gas tank? Did you cap it off? If so, that could contribute to your idle problems. Let me know if you need any more clarification.

Oh, and i have a 98 s13 blacktop type x motor (J4 ECU) and had the same exact problems as you. It's idling great now.

[MrIllegalX]

I have a 98 S13 Blacktop, but running a redtop harness and ECU, and everything is running fine and all, but could any power be made by switching to the correct harness and ecu?

[SpeedRacer1]

If your engine is running properly, then there is no extra power to be made.