patman

iTrader: (3)

Hi guys,

I have been in RX7s for a long time, but havent had any experience with any stock FDs, so I'm hoping I am missing something obvious here.

I just bought a 93, and I am having what fuels like a fuel cut issue. The car idles perfect and seems to run fine, but I get a complete loss of power any time I give it too much throttle. It does not seem to be RPM related, if I nurse it it will rev out. It seems like it shuts down as soon as I hit ~4psi. I see some posts about a limp mode, but I can't find a definition of what the ECU actually does when it goes into this mode. Is this a typical symptom of limp mode, or some other common electrical gremlin, or should I start standard diagnostic procedure?

Just checking to see if it is something simple before I start hooking up all the gauges to try and figure it out.

Thanks,
Pat


edit: no CEL codes, so I guess limp mode is not it.

Zoran_Savic

iTrader: (1)

i had/having the same issue, at first my omp was bad, replaced that now when i get into it hard the car jumps and sputters, i was told the car it running lean or the my throlle position sensor is bad.

amd going to try and unplug it today and see what happens.

if you cannot rev past 4000rpm then you are in limp mode, if u can but lightly touching the throttle. then try what i said, i have a post as well below and hoping that i can fix this asap.

AzEKnightz

iTrader: (24)

Does sound like LIMP mode to me. Check and pull codes first. If there is codes, that's probably what's putting the ECU into LIMP mode.

Update us after pulling codes.

-AzEKnightz

patman

iTrader: (3)

There were no codes.
Tonight I am going to test fuel pressure and run a bunch of fuel injector cleaner through it, we'll see if that does anything.

MOBEONER

iTrader: (18)

Thats what she said!! I tried telling her it was the liquor!!

dimondjack

I have an incredibly similar problem, except that my engine "shuts down" at 0 psi. Does "shut down" boost change at all with RPM? Mine changes to +2-3 PSI above 4,000 RPM.

I was told that it was limp mode, and I actually invested in a PFC (would have probably done anyway) which did not help the problem. I have tested timing, spark, fuel pressure, fuel injectors, and all sensor values. Everything checks out.

My next thing to check is the fuel injector atomization tube on the primary injectors. If this has a leak or is disconnected, I believe that this can reverse the flow around the primary injectors and actually push the fuel out of the injector cups in to the atmosphere. The fact that my problem changes when the secondary injectors kick in make me suspicious that this might be happening.

I really don't have a better answer for me or for you at the moment. If it always happens at the same load (boost), it may be fuel pressure.

patman

iTrader: (3)

fuel pressure is fine. injector cleaner did nothing.

unplugging the line from the MAP sensor fixes it, so I am guessing the MAP sensor may be bad. I am going out of the country for a couple of weeks, will try a new MAP sensor when I get back.

patman

iTrader: (3)

I just tested the MAP sensor per FSM, it is fine. my best guess is that some actuator or output is not working and the ECU sees a feedback loop, then gets mad and cuts power, I just need to figure out what. Either that or the ECU pressure reference might be bad and is seeing 4psi as 12psi and cutting power for overboost.

dimondjack

Any progress? Did you find the answer?

Jedon

I'm having the same issue, it was fine but then the car sat for a few years and developed that issue, complete power cut when boost comes on. I changed the oil and put new gas in. Revs fine at rest, drives normally but when you get on it, POP cut.
It's non-seq with no smog stuff, simplified rats nest, PowerFC.

djseven

iTrader: (56)

Ive never seen one go into limp mode with a PFC, matter of fact didnt think it was possible.

The most common problems that cause limp mode on the stock ecu are the following:
1.No 330 ohm 1/2 watt resistors in the rats nest when going non-seq or simplified sequential.
2.OMP Failure
3. Knock Sensor failure.

To whoever said they had no codes, did you actually try to pull the codes or just assume since the light wasnt on you had no codes? The stock ecu will store codes without turning on the CEL.

dimondjack

For my incident, I actually pulled the codes. There was a throttle position code, but I fixed that (I put the TPS sensor on wrong). When I put the PFC on the car it wasn't throwing any codes.

My PFC has voltages that move for the OMP, has low (but moving) knock values, and I think I still have everything for sequential system (where would that resistor go?). I haven't intentionally changed anything before and after the rebuild.

Is there a way to change over the injector load to the secondary injectors with the PFC? As I said before, it seems to get better (but not good, maybe 2 PSI) at higher RPM when the secondary injectors kick in. This matches my crazy injector atomization tube vented to ATM theory, but that is entirely not proven yet. If I could switch the load over to the secondary injector at low RPM, it would allow me to see if the problem was related to the primary injectors without taking everything apart.

Again, I have stethescoped the injectors (they are running) and looked at fuel pressure, so the injectors should in theory be working.

djseven

iTrader: (56)

With the PFC it is something else all together. The PFC will not go into limp mode that I have found. It definitely doesnt care if the resistors are installed or not.

Mahjik

iTrader: (1)

dimondjack,

Try taking a photo of your Commander sensor screens with the car running and post them here.

patman

iTrader: (3)

i did try to pull codes and there were none. I also took the injectors out and cleaned them, which made the problem worse. I rechecked the fuel pressure and it is at 60PSI all the time, so I think it is just going way rich when the secondaries come online. I am in Sweden right now but when I get back I am going to put in a spare pressure regulator and also get rid of the rats nest to eliminate any potential vacuum leaks I might have missed. (and to make it way easier to work on the engine without all that **** in the way)

If that doesnt work I will take the wideband off of my FC and put it on the car to get a better idea what's going on.

dimondjack

Below are two pictures of the PFC Commander while idling, everything is running just fine. I found it very hard to get a good picture.
https://picasaweb.google.com/lh/phot...eat=directlink


https://picasaweb.google.com/lh/phot...eat=directlink

This is with the car in "silent" mode, where I have floored it, the car is slightly in to boost (just barely), and it has entirely cut out. No combustion whatsoever.

https://picasaweb.google.com/lh/phot...eat=directlink

I am thinking about trying to pressurize my intake to see if I can hear leaking from either the injectors or the fuel atomization pipe. Past trying that I am very lost. If you need better pictures I can try with a different camera tomorrow as well.

Thanks for looking.

dimondjack

Here are two much more ledgible pictures of my commander working and not working. Are these values right? Do these put anyone on a new track?

Car Idling (or close to it), purring along.



After the car was revved up a little (under vacuum), I then floored it, upon which it cut out and I got this screen shot:



The differences I see when the engine isn't running are:

PIM is now 2.78 V vs. 1.51V
Oil Metering now 1.52V vs. 1.25V
Water temp is higher (lower voltage)
Air temp is higher (lower voltage)
O2S is slightly lower

PAC and FPR are now lit, where APR is now not lit.

What of these changes are due to me flooring it, and what are due to something going wrong?

dimondjack

It appears that those pictures may not be large enough. Here are the direct links.


Running:
https://picasaweb.google.com/lh/phot...eat=directlink

Not Running:
https://lh5.googleusercontent.com/-V...2019.11.16.jpg

dimondjack

Seems like I can't get the links right.

The "Not Running" link should be:
https://picasaweb.google.com/lh/phot...eat=directlink

The "Running" link is correct.

arghx

iTrader: (3)

dimondjack,

please create a new thread and explain the entire situation from the beginning while directly attaching and displaying good full sized screenshots. It's difficult to follow what you are saying right now. Datalogit logs would also help a lot, preferably with an accurate wideband. If the budget allows you might as well buy both now.

patman

iTrader: (3)

Well, I removed all emissions, fixed the fuel pressure regulator, added grounds for the block and the ignitor, and drained all the old fuel out and put in new, still the same issue. It is actually worse now. I tried a spare temp sensor in place of both the air and water temp sensors too with no effect.

I did notice today that if I hook up a timing light, it quits flashing when it cuts out, so tomorrow I am going to replace the leading coil with an FC one if I can find one, or a pair of whatever performance ones they have at advance (i checked the resistance per FSM and it was ok, but coils are cheap and known to fail). If that doesnt work I will try crank sensor and ignitor.

I also checked nearly every pin on the ECU, all were within FSM specs. Im starting to get pretty irritated with this thing. I really wanted to drive it in stock-ish form, but if I cant fix this soon I am going to throw away the stock engine management and turbos and go single and standalone.

limepro

iTrader: (2)

Stick to it, took me 3 months to find my problem. Stock twins at 12 psi feels so good, need to take a ride in a single car.

patman

iTrader: (3)

coils didnt help. crank sensor will be here in the morning, but I doubt it will help either, as both sensors ohmed out fine. i'm guessing ignitor, I will see if I can pick one up on ebay or something.

patman

iTrader: (3)

crank sensors were fine, but after messing around with the ignitor, the car quit running and threw a code 2, no continuity to the NE crank sensor. So i'm guessing that the white wire is broken inside the harness inside the fender. I would check but the PO stuck me with locking lug nuts and no key, so I have to find someone to sell me one first.

patman

iTrader: (3)

Finally figured it out, the PO had the trailing coil plugs switched.