running problem, possibly map sensor??
 

alright. so cars running. but it's stumbling at low rpms.... I tried running the car 2 different ways.... i have rtek 2.1, and a stock ECU.

rtek w. 550-720s it idles at 900, at a start in first gear it bogs out than goes, than in second at 2700-3500 it falls on it face and leans out its running at like 15-16 on the wideband. I didn't really go over 3500 when I saw how lean it was, than in third it was about the same stuttered and stumbled at cruise 30-35mph... stopped running it.... I looked at the error or diagnostics part of rtek and it's saying map sensor error.

so than I tried the stock ECU for just the sake of trying it with 4 550s, it idled waaaay better-smoother and was at 7-800. it didn't bog in 1st gear as bad, but was still lean, which I knew it would be, but wanted to see if there was any difference.

so I went back to thinking about the map sensor, I read

BLACK/WHITE 12v
Brown/Red 1-3vdc normally
Brown/White 5vdc
Black ground

I'm getting 12v 12v 5v and .03? this is measuring at the connector with sensor plugged in... tried another one too same thing.

so I guess in the end, could my map sensor wiring be messed up somehow and not sending the correct pressure to the ECU? therefore not compensating for fuel??

I'm not running anything crazy, fmic. stock boost, stock turbo, rev ii exhaust. soooo any ideas?

Did you recently do a turbo swap on this car or switch a harness?

yes it's a s4 vert, all na harness but engine harness is t2

just a thought but could one of the primary injectors be having problems?

That's your problem (and it's an Emission Harness) as the Front from an S4 NA does not match w/the S4 turbo Emission wire for wire. What is happening is the Br/R from the sensor which brings a signal to the ECU splits into two wires. One wire runs directly to the ECU. The second wire would run to the Boost Gauge through the Turbo Front Harness, but you have an NA Front Harness so this Br/R wire carrying the Boost Pressure Signal is mating to a B/W wire which carries a 12 volt current and is backfeeding through the split in the Br/R wire and thus feeding the ECU w/12 volts which is obviously no good. So, you need to cut ( tape off both ends) the Br/R wire at FEM-01 on the Emission side of the harness. When locating this wire you'll see how you have it mated to a B/W wire that has the 12 volts w/key to on. You might have addressed the other discrepancies between mating these two unmatable harnesses or perhaps you have not. The temp sensor not working would be another example of the two harnesses not being mated properly.

yes I knew the temp sensor, and alternator, I did not know the map/boost sensor had different wiring as well. I just really went off rotary resurrections "how to" when it came to the t2 in na. it only mentioned temp and alternator. no mention of map....

this would explain the odd 12v.

Read through post #10 in the link supplied to check if you made all the proper adjustments.

https://www.rx7club.com/2nd-generati...ps-vss-550937/

thank you. that link is perfect.

IF you mate a TURBO EM harness with a NON TURBO Front harness the boost sensor output will mate with a wire on the Front harness that comes from the METER fuse, if memory serves. That act backfeeds the boost sensor AND the ECU pin 2B with a constant 12vdc signal any time the key is to ON or better.

To fix that, the brown/red wire in the plug called X-15 needs to be cut off about three inches back from the plug and capped off.



so does this mean the Brown/red wire does not need to be repined? just capped off? I can see he wrote to do that, I just don't wanna start cutting things....

just capped at both ends(shrink wrapped), to prevent it from shorting to ground and blowing out fuses.

It means you would just cut it off and tape both ends. The Br/R wire coming from the Emission side would only be rerouted if you were to run it to a Boost Gauge. Make sense?

ahhhh alright. perfect sense now....