Sabersupra

A friend convinced me to try out Map ECU 2 for my build on a 98 GS 300 that I've turboed. We're running the Aristo upper Intake Manifold welded to the bottom of a GE which seems to work pretty good. Before we installed the Map ECU 2, I was able to go into boost with just a few pounds, but not WOT. The injectors were stock and the car would lean out and break up. Now with the Map ECU 2 installed and bigger injectors, I'm not able to boost without the car breaking up. The AFRs are about 11.5 when boost comes in and we played around with timing a bit to see if that is the issue with no result. Now, with the MAP ECU 2 hooked up, he scanned the car and found a Water Temperature Code and also 1 Primary o2 sensor reading lean...... Is it possible that the malfunction of the O2 and the Water Temp Sensor could be affecting the car when it hits boost? When the car boosts, it sounds like a really fast anti lag setup (which it's not) and you can tell that something is wrong. We're trying to sort everything out on the street before booking dyno time that will be a waste if not fixed. A previous mechanic apparently joined the primary o2 sensors together. He said that this would actually help the car run better with a piggy back. I've never heard of this but I've been told that he really knows these engines. Any ideas on what can be wrong???

99 GS3

iTrader: (14)

What injectors, and are you trying to use the o2 skew function?

And don't join the o2's together, and exactly how did he do it. Is it just both sensors tied together and feeding both ecu inputs, one sensor feeding both ecu inputs, or what? Undo that o2 splicing **** and get the car to a legit tuner and pay the money to get it done right. As long as you have a fuel pump upgrade, bigger injectors, fpr, verified good coilpacks/wires, and new plugs along with the mapecu wired in properly it's ready for a real dyno tune.

If it feels like it hits a wall when it starts to boost and/or sounds like you mentioned, it's because it's not tuned and just pissing fuel.

Sabersupra

Thanks for the quick reply.
Bosch 630cc & not using the o2 skew function
I believe it's both tied together feeding both inputs.

I just want it to be able to boost again and I will definitely get tuned properly. I'm debating if I should use my AEM FIC though.

badblackgs

iTrader: (1)

I'm wondering if perhaps your MAF signal is pegging out. It would be worth data logging. Or maybe even try unplugging the MAF sensor and see if it does the same thing. With 11.5 AFR and the engine breaking up its also possible the ignition is going bonkers. Start with the MAF signal. have you altered it in the Map ecu? is your maf sensor housing stock or in a aftermarket cold air pipe?????

99 GS3

iTrader: (14)

Tying two active o2 sensors together is not helping anything, undo that and hopefully he didn't make a complete hackjob of the wiring doing so. That isn't doing anything but screwing up the readings. Now sending a single o2 sensor's data to two inputs is another topic that has it's uses.

Is any of the o2 inputs ran through the mapecu? (its not required by the mapecu, but would be to use o2 skew)
How did you set the loading for the mapecu? i.e. MAF/MAF or MAF/MAP or are you running MAF eliminate?

The FIC works well on these cars when tuned by someone capable, as does the MAPECU2/3.

Sabersupra

We first ran the car without the MAF or o2 sensors hooked up. We were able to set up idle, start and cruise quite well. The only problem is when boost comes in. Eventually when we put the MAF and o2 back into the equation. It's taking some time to re-tune the car because we were not expecting that issue.Waiting for warmer weather to try again.

Sabersupra

At first hookup, we eliminated the o2 sensors and eliminated the MAF. We will try out the MAP ECU 2 again when the weather gets nicer in Toronto.
Can the Water Temp Sensor malfunction cause this issue? I'm really lost here but don't want to switch to AEM FIC if this can be solved. It seems easier to tune. I tried doing a search for other MAP ECU users running NA-T. It seems that quite a bit of members do the ARISTO swap so there may be some differences that I'm not aware of.
I'm wondering if the mechanic sent a single o2 sensor's data to two inputs? I can't even get any info from the person that did the work since he does not want to get into modifying any longer. Just wants simple jobs . I'm wondering if the two o2 sensors are tied but there is incorrect spacing due to custom down pipe, would that cause a code that could affect boosting? Or there is 1 sensor providing data to two inputs which should be different readings and causing one input to look lean .

super51fan

Why dont you run your car on the aristo ecu? You will need a gte map sensor, gte maf sensor, and aristo trans but you will have a car that runs like factory with minimal wiring

99 GS3

iTrader: (14)

A malfunctioning temp sensor defiantly affects the ecu. The MAPECU is plenty capable, when done by a tuner that has experience with the both the GS ecu and MAPECU, it's a good piggy just not as common in the states or much outside of the non-vvti 2j supras. The vvti GS/IS ecu's have two maps for hot and cold starting, and will also default to a fixed map if the primary o2's are disconnected. All this needs to be accounted for tuning the car. Trying things by changing thing on engine/maf/o2/temp items is starting from scratch again each time. You will have better luck researching diy piggyback tuning a vvti ge ecu on the my.is forums, there is more in depth information and threads about it there.