DivineOne

Car: 1990 GXL

Problem: Only idles cold. Idle slowly drops until coolant temp reaches 150°F, then it will not hold idle afterwards.

What does work: When I energized the AWS solinoid in RTEK, it can idle when coolant temp is past 150°F. I can drive the car normaly. The idle becomes a steady 1200 - 1300 rpm. The idle likes to bounce when clutch is held in this mode however.

What's done so far to it: Catless, checked for vaccum leaks via starter fluid spray(hoping to get is smoked tested later), new Intake gaskets, new ACV gasket, all new silicone vaccum lines, new battery, new spark plugs, and new 02 sensor.

Thanks for reading. Any suggestions would be greatly appreciated.

Here are some readings from the rtek if it helps. The readings are at idle.

DivineOne

What I've done so far :

• Pulled a vacuum on the brake booster (was good, held vacuum)

• Compression checked it when warm. Rear rotor PSI (104,100,103) at 254rpm. Front rotor PSI (111,108,107) at 254rpm. (used rotary compression tester.com device)

By this point I had an issue connecting the RTEK to the Palm as I was checking to see if it would throw any codes at me. Took out the ECU to check it. Found this. Going to the junkyard tomorrow and try to find a N350 ECU. Then go from there.

My Questions:

• What could have cause this? (so I may be more careful in the future)

• What ECU can I use besides N350? ( I am having a hard time online and in junkyards for this exact one)

• Is this repairable? ( I have some soldering skills and a multi-meter)

gatesrex91

iTrader: (2)

I assume the issue you are referring to is the area of the ECU board that looks burnt? I cannot tell from the pictures if any of the actual connections/solder joints were broken? I see those little green wires which I assume are added by RTek but again, I can't tell if any of them are not making connection.

What injectors (specifically high vs. Low impedance) are you running? I know there can be issues with damaging the ECU if it is seeing the wrong injector impedance (and resistors need to be run to correct that).

I dont have any solutions for you but I am curious on how you are able to fix your idle issue as my 88 T2 (also running an Rtek 2.X but with N333 ecu) has the same issue. It idles fine on initial startup but struggles to maintain idle and often stalls once up to full operating temp. It was like this when I bought it and I have not had enough time to dig into a fix yet.

I also don't have the rtek software so the palm that came with the car (with dead batteries and therefore no software) is worthless to me. I bought a spare Rtek 1.8 ecu which should run my 720/750 injector setup fine, but I have not tried swapping that to see if it helps the idle issue.

I also suspect it could be the tps so I grabbed a spare one as I did not have any luck when I calibrated the current one (it actually got worse) and plan to try that out soon.

I also need to do a compression test, but it will be with a piston tester as I don't have access to a rotary specific one.

curious to follow this thread to see what fixes your issue.

DivineOne

I'll post more details in the next update post

Ah, sorry about that. I'll post more of the internals of the ecu in the next post.

Have had the stock injectors since I've owned the car. They have been cleaned, and I installed new filters and grommets since, but I'll double check and make sure they are the S5 high impedance ones since I'm going to take the intake off again.

I still have all my files when I bought the RTEK. Just PM me your email and I'll send them your way. Though, it's everything from the version 2.0

I also plan to go back to the tps, once I've thoroughly cleaned and redo the entire throttle body. Details in next post.

DivineOne

What I've done so far :

• Installed new ECU. (N352-18-881R)
• Smoked tested the intake via vacuum nipple AFTER the throttle body. (The only leak was the air pump hose which connects to the air filter box) I put with a hose clamp instead of the stock ring clamps

Problems:
Still does the same thing. Doesn't Idle after it reaches temperature. Currently, I've tighten the throttle cable just slightly so it can hold the idle without my foot on it. Drives fine and gets me around like that but I am not sure if its supposed to be like that.

Questions:

• The throttle cable should not have anything to do with the idle right? (cause I've replace it recently as it had ripped when pulling the engine. Currently have it tighten enough to hold idle)

Whats next:

• Completely clean, disassemble, reassemble and readjust the throttle body. Including all the idle stuff like TPS, check BAC again, fast idle (My idle speed screw does nothing by the way)
• Clean AFM
• Install new Coolant Thermosensor (since they're cheap)

Pictures of the burnt ECU below

• Where the RTEK is burnt where it says "IC603"
• On the PCB which the harness plugs in to...the T811 spot is burnt. it has these letters on it "E1A38 K399"
• On the PCB which the harness plugs in to...the "3R9J 1w" is burnt.

gatesrex91

iTrader: (2)

oh awesome! That would probably allow me to get the rtek app back on the palm that came with the car.

I'm not sure if my ecu is a "2.0" or a "2.1" (I'll have to pull up the carpet and check next time I get some time to work on it). Once I confirm I'll PM you my email.

Not sure if your 2.0 palm software would work if I have a 2.1, but its def worth a shot! (As it stands now the ecu is stuck on whatever settings the previous owner had it on as I have no way to get in through the palm since palm memory wipes when batteries die).

Question: If I was able to load your rtek software on my palm, what would happen when I plug it into my existing ecu? Would it revert back to "initial set up mode" as if I just bought the rtek? Or would the tune/settings from the previous owner still be there? I'm not sure of the details of stuff like that on this old school rtek platform.. if you have any insight on that it would be much appreciated! Thanks!

gatesrex91

iTrader: (2)

so the hot idle issue is likely NOT linked to the rtek ecu (or the burned areas of the rtek ecu's board) since you tried another (stock) ecu and it behaved the same...

You said you couldn't raise your idle with the adjustment screw at all? Do you know why turning the screw wouldn't allow you to raise the idle? My idle adjust screw is built into the bac valve (as was standard on the 88 t2) but I have not messed with it yet (that was going to be last resort if messing with different ecus/tps settings, new plugs/wires, etc. didn't work).

Tightening the throttle cable so the throttle stays slightly open when foot is off the gas is a great potential workaround to keep the car drivable until I can figure out the root cause, I may have to look into that option too! It idles fine when cold before the thermowax kicks in, so I assume slightly tightening the throttle cable to keep the flap slightly open when warm would have similar or same affect to how the thermowax keeps it slightly open before fully warmed up.

I'll def keep following this thread!

DivineOne

All the tune, adjustments, and settings will still be there that was set by the previous owner.

There are more info on the PDF files they provide with everything you need to know here "https://digitaltuning.com/index168a.html?pid=rtek7", check it out if ya still have more questions^^

Also RTEK has a way to "Reset ECU" function in its drop down menu that restores the settings to factory. This is my experience in the S5 NA N350 Ver.2.0 ECU, but I believe they all use the same Palm software that is provided when you buy it.