Rich Condition upon ECU install

[Bobbymudd]

Hey Guys, have another issue that im hoping the combined knowledge of the forum can help me figure out.

Have a 91 TT 5spd that ive had for about 3 years now. It has 90,000 miles and ive done all the preventative maintenance, 120k Kit, spark plug, New OEM injectors, new OEM fan and fan clutch, new knock sensor in OEM location, etc. then I started to do some performance stuff, downpipes, testpipes, catback, an upgraded RPS clutch, an intake, ETC. So in my mind the next step was to do some light tuning. I bought a used ECU off a forum It was for a 1990, TT, 5spd Cali emissions. I live in Missouri but was told that when i replace the Eprom chip in that ECU it would wipe out the Cali emissions portion and i would be all good. Then Bought an upgraded chip off a forum that was exactly what i was looking for. 5spd, single intake, stock injectors, etc and it was supposed to be safe up to 15 psi. It was also from a reputable tuner, Harry at Z tuner. I also called and talked to harry to confirm the details of the chip. Then i went out and bought the 12-13 psi boost jets from concept Z because i wanted to be safe and make sure i avoided detonation. So when i had it at the shop for some smaller stuff they agreed they would do everything besides socket my ECU and install it. So i agreed id have that done elsewhere and id just drive the car easily since it would have the boost jets installed on a stock tune. Got the computer done and installed it and had some issues. While at the shop i had them install an AEM wideband. On my stock tune at idle the AF is right in the middle at like 13-14. When i installed the new computer with the tune it started but ran kinda rough. when i looked at the AEM the AF was maxed out rich at 22. So i put my original computer back in an have just been driving it easily. So any suggestions for testing? i dont know a ton about tuning but from what i understand the Eprom chip controls the fuel map so the problem is likely with the chip and not the ECU? Any Ideas would be really helpful. Also tell me if this is to be expected. This is my first experience with tuning so i didn't know what to expect. Thanks again guys.

[NolimitZ32]

Not necessarily the chip, it could be the ecu, do you still have the original chip that came out of the ECU, if you do try installing it in the socket and see if you get the same results.

[Bobbymudd]

Thank you for they reply, I do still have the original chip and I will try that this weekend hopefully and report back. Thanks again!

[Bobbymudd]

Hey I apologize it has taken so long to respond. I went through a move and it has taken me a long time to go back through all my boxes.... and unfortunately I cannot find the original chip out of that ECU.

So Another thought here. I already have the Concept Z 12-13 psi boost jets in the car. Im thinking i might just send the whole ECU into either Z1 or Concept Z and and have them sort it out and then have them install their own performance chip tuned to my cars intake, injector size... etc. So is there more work that goes into tuning an ECU than just changing the eprom chip? for example will I notice better performance out of a car that has had an entire ecu sent in as opposed to a stock ECU that has had a socket and aftermarket eprom chip installed? Or are they just charging extra because they are adding the socket?

Which company would you guys recommend? Z1 wants like 200$ for this. Concept Z wants like 150. I know Jim wolf is the best but he wants around 600$. is the quality difference worth it or for a car with only mild performance upgrades? Or will one of the other two suffice? Id prefer Concept Z because ive had issues with Z1 before. Its a 1991 with 90k on it. single intake, new oem 370CC injectors, z1 downpipes, testpies, cat back 2.5 inch. new RPS clutch. currently i've been running it with its stock ecu with the boost jets installed and have just been taking it easy on her.

Any input is greatly appreciated, thanks again guys

[itsa300zx]

I vote for specialty Z

[NolimitZ32]

I don't know if I'd necessarily say JWT is the best. They are definitely a top player. Best is a dynotuned standalone but you're looking at around $2-3k for something like that. Whether you send in the ECU or get an EPROM and install it yourself the process is physically the same, if you send them the ECU they will take out the stock chip, solder in a socket bed and install a tuned chip. You never said anything about who socketed your ECU, are you sure this was done properly?

[Bobbymudd]

Hey thank you for the responses. Well no limit, I cannot 100% confirm that the socketing job was done correctly, as I am not very knowledgeable about soldering. However I took the ECU to a place that builds custom PCs so it seemed like a reputable place. In addition they seemed very confident it was within their skill set. So in my mind the fact that the car started and ran (even if not great) would seem like reason to believe the solder job was done properly, yes, no? That’s just what I was thinking, does that sounds right to you or are there other factors I might be missing?

thank you for answering my question about sending an ecu in versus buying a chip. I also talked to someone at SZ and he believed that because the car started and ran the ECU was probably okay and the EPROM chip was more than likely the culprit in his mind. He said if the EPROM chip didn’t fix the issue I could send in the ECU and they would take a look at it for me. I have ordered the SZ chip and will post the results. Thanks again for the help.

[NolimitZ32]

That all sounds about right. I just brought up the socketing as something to not be overlooked.

[Bobbymudd]

Hey guys, another update. So my chip from specialty Z came in. I installed it into the car and was having a ton of issues. Even though this is embarrassing, I hope that by me posting this it may stop someone else from making this same mistake. So because I had no idea there was a correct orientation on the chip, I popped the old one out and put the new one in what turned out to be upside down. After contacting SZ they asked for a picture to be sent in and confirmed it was indeed installed incorrectly and are sending me another chip at a reduced price. I have come to learn that the chips have a half moon indentation on one side and that should be matched up with a marking on the board. If you are unsure you should reach out to someone more knowledgeable that I to ensure you don't fry your chip like I did.

On another note my car displayed an interesting/worrying symptom while I was running it on the fried chip. I ran it for about 1-2 minutes with the bad chip in the car. it was missing and just generally running terrible. I then took the ECU out and swapped back in my stock ECU and then pulled the car out into the street. upon returning to the garage I noticed a gas spot on the garage floor about as big as a dinner plate. I immediately went back out to the car and searched for an area that looked wet. the area by the fuel pressure regulator and the area under it looked very slightly wet but not obviously wet. Next I got a fire extinguisher and a flashlight so I could start the car and look for the gas leak. started it and not a thing leaked, I then drove the car the rest of the day with the fire extinguisher handy after thoroughly checking the car and there were no leaks the rest of the day. I know how crazy this sounds, also this liquid was 100% gasoline. I do occasionally have condensation that will leak out of an exhaust joint. I thought maybe because the car was misfiring gas was going out the exhaust, and then dripping. Well unfortunately they are not the same spot and the gas spot was directly below the back of the engine. I talked to SZ and they said they had never heard of a fried chip or any other computer related issue causing a gas leak. They said there was nothing in the tune that would affect my aftermarket fuel pump either. I'm really at a loss on this one guys. Just wondering if you have experienced anything like this or if you have any ideas. Thanks again guys!

[NolimitZ32]

Its getting cold, your fuel line connections probably contracted and let some fuel go before they warmed up and resealed themselves. Go through and tighten all out fuel line clamps.