Gargamel

While in neutral my car starts to boost up to 10psi around 2G rpm's. The car is bone stock with a downpipe. Complete non sesquential conversion has been done and all connectors replaced with resistors. No codes are being pulled at all. We've tried a power fc with no luck. The car did this before being tampered with.

It thought it might be in the crank angle sensors. Anyone know of a way to check continuity from the connector to ecu?

What would make it boost in neutral at only 2g rpm? Doesn't advancing it make it do that or something similar?

Thanks...

Roddimus Prime

I was under the impression that boost could only be built under a load as in driving. Is your car an automatic? You said it does this in nuetral also?? Strange. I'll ask my local guru.

Gargamel

The car is a 5 speed. I think my problem is in my ignition somewhere. Anyone have some insight to where?

rx7raca

its impossible, no matter what transmission or ecu or any kind of timing. you can NOT boost. maybe one or two psi, but no way your getting 10psi. something must be wrong with your connection on the boost gauge. is the gauge aftermarket?

dubulup

4psi if you rev high in nuetral...seq set-up.

maybe calibrate your boost gauge.

$150FC

rx7raca,
it's not impossible. one of the FC guys (Carx7?) was building ~8psi by revving in neutral.

and you can do it through a standalone, which alters the timing. it's called 'antilag.' Another one of the FC guys (87GTR) has a video of it in the second gen forum.

and the boost gauge has to be aftermarket. obviously.

now.
gargamel,
anyway, what's the problem? Does the car feel normal when you drive it? if your only problem is that you can rev and build boost, then...i just don't see an issue.

if the boost gauge is improperly installed then it will just read 0 all the time. Unless it's an electric gauge and then i suppose something could be haywire which would cause incorrect readings.

victor

Gargamel

It's not a question of whether or not it's doing it. The question is why.

Have you ever seen a car with a 2 step on it? It does something with the timing so that you can boost in neutral or with the clutch down. My car acts like that. The gauge isn't broke.

Greys 10th

When i rode in SPOautos( stephen ) his car would boost to around 10 psi sitting at a stoplight in neutral...he revved it up higher than 2K though...he said a car with no cats and a intake would do that cause the turbos are breathing much easier. I might have botched the explanation up, but i know for sure he boosted in neutral i am guessing it was high psi the BOV vented a lot of air.

Gargamel

Trust me, the gauge is fine. I cannot drive the car as it sits. As soon as it revs to 2g rpms the turbos are screaming and it pooring black smoke out the exhaust and basically it won't go over 2G rpm's because it wants to back fire and pop. Reminds me of a car on a two step if you've ever seen or heard one. It's just dumping fuel. Stock injectors, brand new reman, brand new $3G mazda turbos.

$150FC

yeah, i mean, you can do it, but (probably) not at 2k.

(how'd you like stephen's car, Grey? )

gargamel, if you have the stock ecu then you shoulnd't be able to make it act like a two-step. Are you just revving in neutral? Does the car rev as high as you want or does it stop at 2k and build boost, like a 2000rpm rev limiter, almost?

Gargamel

I can't go over 2,000-2,100 rpm. It builds boost to 10psi and backfires. When it backfires, the check engine light will quickly blink once.

I know that I can't make the stock ecu into a 2 step. I'm just saying that I think something is wrong with the ignition that is making it act like a 2step.

$150FC

OH. Ok. You didn't say that.

That's weird. checked your coils? spark plugs/wires?

Gargamel

Very weird....it's a freak.

Spark plugs and wires are fine. Haven't checked coils or ignitor yet. Anyone know how to do the following?

1. Check coils.
2. Check ignitor
3. Check Crank angle sensor, wire to ecu continuity so there isn't a break somewhere?

P'cola FD

I would check the ecu for trouble codes. It sounds a little like limp home mode, except, you can't build boost in limp home mode. If you don't have any trouble codes, I would say to check all the sensors connections. If you have spares or another FD swap sensors out one by one to see if a change is made. Also, check the crank angle sensor pulley. If that thin little bastard is bent, which isn't uncommon, it can take you on a wild goose chase. If none of that works, you may want to go throught the wiring harness, checking that all grounds are good, and there are no shorts.

XSTransAm

sure your tach is reading correctly and 2k isnt 8k?

Greys 10th

oh it does look like you have a problem after you got more descriptive about it....doesnt sound normal....sure someone can straighten you out 3rd gens are out of my trritory.
oh a Vic of course i loved it.....what i was talking about the boost in neutral thing that was back before the first rebuild with just bolt ons lol.....no that car makes as cool as the noises that one makes

P'cola FD

You can check the ignitor and coils with an ohm meter, but that isn't necessarily a definitive way to say that they are good. Easiest way is to swap out with a friend's car. For the CAS wire continuity, get an ohmmeter a factory service manual, and a friend, and put one lead on a terminal in the CAS connector on the harness, and the other lead on the corresponding terminal on the harness going into the ecu.

Gargamel

Without looking it up. Do you know if the wires from the crank angle sensors go directly to the ecu?

P'cola FD

yes they do. I've actually pulled an old harness apart, and I remember that they went all the way back, because that grey shielded wire goes all the way back.

Gargamel

There are no codes. I even tried a power fc with no results. I've check the harness and didn't see anything visibly wrong.Remember, I only have 3 solenoids underneith after doing the no seq so most of my potential problems are out of the way. I've also check the crank angle sensor pickup pulley and it's fine.

Gargamel

I'll be checking that. I'm just going to swap out the coils and ignitor from another car and see if that helps.


Anyone know what a 2 step does that makes it build boost under no load?

Gargamel

Positive

P'cola FD

I'm pretty sure it retards the timing a lot, and dumps a lot of fuel while setting the rev limit low enough for a good launch.

Gargamel

maybe someone secretly installed a 2 step on my car as a sick joke..... hmm

Gargamel

Anyone know what would cause the timing to retard? Wouldn't the timing retard if the crank ange sensors weren't hooked up correctly?