Osirus9

iTrader: (10)

So the basic problem is that i get fuel cut at 3500 rpm under load only. I have an rtek chip that lowers the firing of the secondary injectors to, you guessed it, 3500rpm.
i can freely rev all the way to redline no problem in neutral or while driving without building boost, but under boost it will cut fuel and i will not be able to get past 3500 rpm under load at all.

now that this is clear, I have checked all my grounds, and checked with a multimeter for resistance, which i get at an ohm or less pretty much all around.

the kicker though, is that if I pull the fuse for the gauge cluster (coolant gauge, tach, fuel gauge, etc..) the problem goes away COMPLETELY.
I however, enjoy having gauges and would like to have them working if at all possible.

I have tried swapping out gauge clusters with no affect.

I also have a wideband installed and can see the AFR's remain good throughout the rpm band with this fuse pulled.

Does anybody know what could possibly be causing this?

g14novak

iTrader: (1)

How much boost are you running?

Is this in a S5 or S4?

Unless I'm mistaken, their is no actual fuse for the gauge cluster, but the one your refering to is the METER fuse? It also controls the cruise control system, idiot lights, and cooling fan (for the A/C system) among other things.

You might want to start looking at those and see if you have any loose grounds anywhere.

Osirus9

iTrader: (10)

i forgot to mention that this is an s4 turbo.

and yes, i believe that it is the meter fuse, but i lost the fuse box cover so i didn't know the correct terminology.

the car came stock with A/C and cruise control but I have removed both of these systems. could having the plug for the A/C fan unplugged cause a short, or maybe having the cruise control switch removed?

by the way, where is the cruise control CPU and could i unplug and remove that as well?

Jimmy2222

iTrader: (3)

What other mods are you running other than Rtek?

Osirus9

iTrader: (10)

i suppose it's worth mentioning that this problem pre-dates all my electrical mods, but i have an safc2, wideband O2, rtek 1.7, 720cc secondaries, 255 venom fuel pump with re-wire, s5 alternator with re-wire, and thats it for pertinent mods i can think of.

I should also probably mention that my old wiring harness (behind the dash and driver's side of the engine one) was totally shredded by a "security" system and caused my battery to drain in about 5 seconds.
I have since replaced it with another s4 turbo wiring harness, and this is the only electrical issue i have run into with it.

HAILERS

Sounds to me like you have unauthorized power from the Meter fuse going to the boost sensor input wire at pin 2B. Kinda unlikely but I'd check the voltage at 2B by backprobing 2B with a meter and at idle compare it with the manual. If it reads anywhere near batt voltage theres a miswiring problem. Normal voltage is Never over 5vdc and most of the time less than 2-3vdc.

A better bet is the secondary injectors are not plugged in. Simple to find out. Leave everything connected and back probe the small plug of the ECU. The light green/red and light green white wires. Should show batt voltage if the plugs are on the injectors (secondary injectors). Even one plug off would cause your problem.

Then again, pulling the Meter fuse fixes things.........so it must be a miswire. Meter fuse has zippity to do with engine management. It can only cause problems if the boost wire is miswired and backfeeding over 3vdc to the boost sensors output and the ECU's input.

Makes no sense. Gotta be a miswire if the METER fuse being pulled *fixes* the problem.

Osirus9

iTrader: (10)

This is what I was thinking HAILERS, and I have already tested to make sure that the secondaries were plugged in with this method and they are.

I will test the boost sensor at the ECU, but I have already tested it at the boost sensor itself and got within spec readings when the car was running and i was blowing into the boost sensor to create "boost".

How would I go about finding such a miswire?

HAILERS

How about pulling the plug off the instrument cluster that has the BLUE/WHITE wire. That's the boost sensor input to the gauge. Then leave the meter fuse in and go for a ride to see what happens.

If you checked the boost senor at the sensor (brown/red output wire) then that should do. Might do the ECU pin 2B though.

Fuel cut is determined by the ECU when it sees a certain voltage or voltage above that voltage. I think that figure is??? 3.3vdc???? But the RTEK should have taken care of that and ignored that voltage figure.

EDIT: That's the funny part. The RTEK 1.7/1.8 are supposed to deleted fuel cut by the ECU. Shouldn't happen.

Actually, the more I think about it, I'm clueless why the thing cuts fuel with the METER fuse is pulled, becasue the RTEK should not be allowing that in the first place.

Osirus9

iTrader: (10)

I'll give that a shot HAILERS when I get a chance to work on her this friday.

as far as why the Rtek is allowing for fuel cut i'm as stumped as you are. adding an aftermarket FCD has no affect either.

Osirus9

iTrader: (10)

removing the plug on the back of the instrument cluster with the blue wire with a white stripe had no effect other than turning the warning buzzer on, however removing the other plug (the center one next to the speedo cable) had the same effect as pulling the meter fuse.

I was testing the car with my friend in the car this time and he was able to look at my safc and i was wrong about the problem being totally fixed. it cuts at 5700 rpm instead of 3500 with the meter fuse pulled/center plug pulled.

misterstyx69

iTrader: (142)

I just wanna toss something at ya.
have you ever thought that your Safc is not wired correctly?..Can you recheck the wiring?
My thinking is that the RTEK should prevent Fuel cut,.but the SAFC is refining maps,so maybe it is doing somethinhg it shouldn't.
It's just a Off the wall Thought,Use is or Throw it out!.Cheers .

Chris Boots

I'm agreeing with HAILERS on this one. if it was a rtek 2.0/1 id say tell me what kinda boost sensor readings you're getting but in this case do what he said and tell us the voltages you're getting to the boost sensor. One thing you can also try (but not for very long cause its probably not good) is unplug the boost sensor and see if the problem goes away. unplugging the sensor will set its input in the ECU to a default setting/reading similar to "limp mode" on the S5's but not quite the same. Its easy to just unplug the boost sensor really quick and drive a couple blocks and if the problem goes away that tells you you're wiring is boost sensor related.


although... still confused with your problem cause rtek removes boost cut too... hmm

HAILERS

The *other* plug has the b/y wire which if the wire from the Meter fuse. So pulling that plug is the same as pulling the meter fuse. Kinda proves it's the instrument cluster causing the problem, though (via the meter fuse powering *something*).

I'm a little lost here. Maybe pull the SPEED SENSOR wire out of that plug and have a go?

I WAS kind of leaning towards removing the SAFC til I noticed this.

HAILERS

Mabe the rev limiter is screwed up. I know verrrrrry little about the rev limiter but have seen posts on this site on how to *over come* the rev limiter.

HAILERS

Eh. Ignore me altogether. Japenese cars have speed limiter, USA cars don't. I think both versions have a rev limiter but is most likely in the ECU itself. Got me what's wrong. Maybe remove the SAFC or unplug it at the SAFC itself and go for a ride as the man above suggested.

anthonywe

also having a problem like this.. car will not go higher then 4 rpm. I used some fuel injector cleaner in the tank and after a while it worked better. At work now after here I I'm driving the car to some one to have it checked but looks a bit like it can be something with not enough fuel in the motor or something like that. Maybe I have a different problem that you have not sure. Maybe try having the fuel injector cleaned? That is what someone suggested me so I will see later today what they do and tell me and if any solution I will post. good luck with your car

Osirus9

iTrader: (10)

If my injectors were clogged then I would not be able to influence this issue by unplugging my gauge cluster.

In any case, how can I test to see which wire coming off my gauge cluster is causing this fuel cut issue?

I really don't want to remove the SAFC because the wires spliced in are really short already, and i really don't see how the SAFC could possibly be responsible for this...

Mo_Jo_Jo

I've seen an AFC do some really wierd things with a car (not RX7). Gotta remember that simply unplugging it won't work because it takes inputs from a few circuits (wire from harness -> AFC -> then ECM).

Osirus9

iTrader: (10)

meh, alright i suppose i'll try removing the safc as i'm pretty much out of options...

misterstyx69

iTrader: (142)

.I gotta subscribe to this thread!.
Pm me if I guessed right!..I can't fix my own car,(a vacuum leak hiding in my engine!)but it would be nice if I helped fix someone else's!.

Osirus9

iTrader: (10)

^lol i'll let you know if the SAFC was the culprit all along

Osirus9

iTrader: (10)

just removed the SAFC tonight, and not really to my surprise...

nothing happened.

It runs the same since the SAFC wasn't set to do any corrections, and i still get fuel cut at 3500rpm

lastphaseofthis

iTrader: (8)

I'm Having the same problem. It is only when the First psi of boost comes on, i can drive the car perfectly normally if i stay out of boost, my car's completely stock ECU wise, plus a FCD that is plug and play, and currently removed. see my thread for what i have tried so far:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/fuel-cut-something-simular-1psi-stumped-859284/

I took mine for a test run without the FUSE for meters, nothing changed...

Osirus9

iTrader: (10)

Your problem is a bit different than mine, since yours is related to boost and mine is based on RPM. have you tried replacing/unplugging your boost sensor?

lastphaseofthis

iTrader: (8)

Yes, tried running with out it, tried to set it to -10 psi( i know) and then drive with the computer seeing -10PSI the hole time and it still does it. which is really got me stumped. it's also at low rpms as low as 2200 so i know it's not the 2ndary injectors.

i did put a volt meter on the fuel pump and go for a test drive, it stayed at 9.25-9.54V the intire time, even when the fuel cut hit.