69trgt6

OK, quick backround, hen the question. My little brother is in Iraq, he bought a '94 RX7 from a guy in Buffalo, that had it serviced in Rochester. He bought it sight unseen, but it was advertised as all stock, needs nothing. I picked the car up and drove it home to the Albany area. ON the trip home, the car barely made it. The check engine light came on and the car would not rev (in neutral or driving) over ~3,000 rpm, it would just fall on it's face if I tried, it would also fall on it's face if I put my foot too far into the throttle. I did a bunch of research and I was told that it sounds like the OMP was bad and that the computer was limiting the engine to prevent damage. I found a used, but good OMP for a decent price. I took everything apart and finally got the old OMP off the car, but could not get the replacement OMP back on without removing the turbos. So, I made a block off plate, and plugged the replacement OMP into the harness, but it's not hooked to anything. This cleared up some of the problems, and Yes, I'm premixing 2 cycle oil in the fuel.

Now the car will rev up to 7000 rpm in neutral, I can see the turbo hoses to the intercooler expand when I rev the engine in neutral, so it's able to build some boost. But, when I drive the car, the check engine light is still on, it will rev to over 5000 rpm when driving (I stopped there just because, it could probably go full range). It spits and sputters if I get to far into the throttle though, doesn't matter if I'm driving or it's in neutral. Just seems that there is a point that the TPS cannot go past. I warmed the car up yesterday and checked the voltage on the TPS the way I found to do on here. Both readings at close throttle were in range, but both values at WOT were low, about half a volt lower than the low side of the listed range.

Is there anything else that I should check into? I'd like to get this car running the way it should before my brother gets home from Iraq. And hopefully it's not going to cost an arm and a leg. I'd hate to think that my brother was ripped off...

Thanks,
Greg

BoostedTimmy

If you haven't already pull the codes from the ECU. You need to adjust your TPS if its out of range, just play with it for a while until you get all 4 ranges in spec.

gracer7-rx7

iTrader: (16)

Yep. Should have been the first thing he did rather than rig things up as they have now. I highly doubt the OMP was at fault.

69trgt6

Well, first thing I did was take it to the dealer, I know, that was a mistake. All they were able to do is identify a major oil leak at the OMP and they told me that they found a communication issue on one of the wires to the ECM.

After plugging in the replacement OMP, the symptoms have definitely changed.

Is there a way to read the codes other than a scan tool? I plugged a Snap-on scan tool into the car last week and it didn't show any codes, I'm not sure if that's related to the communication issue that the dealer identified.

Now, I'm not new to cars... I have 25+ years of experience working on cars, building motors, transplanting, etc... I'm just new to RX7s and rotary engines.

Any help that you can offer would be appreciated

tiger18

iTrader: (1)

Basically mate your car is in LIMP MODE,, and yes the oil metering pump can cause the car to go into limp mode but its probably 1 of many electrical sensors on the car that can. You should have first pulled the ECU codes to find out what the fault is. Read here mate to do a code pull.
http://www.rx7city.com/ecucodes.htm
Just out of curiosity have you tried disconnecting the battery for 40 seconds to reset the ECU and clear the codes?

69trgt6

Hey, thanks for the help with being able to pull the codes. I hope that the communication issue that the dealer said exists doesn't present a problem. I'll try to pull those codes and let you know what I find.

Thanks

Sprockett

You seem to be (refreshingly) the most knowledgeable noob on this forum in a LONG time. Congrats, and I truly hope you figure out the problem. Definitely sounds like it's in limp mode, though - that's what I figured it was when you first mentioned the 3000rpm thing.

69trgt6

OK, no luck getting codes. I'm assuming that the "MIL" that is refered to in the code pullig proceedure is the check engine light on the dash? If that's the case, when I have the TEN and the GND jumpered together, turn the key on, the check engine light turns on for a few seconds, turns off for about a second, then comes back on and does not flash. The dealer said that there was a problem with pin 1F. All Data says that terminal 1F is the self Diagnosis checker (code number). From a wiring schematic, it looks like pin 1F on the PCME goes to a connector (that is unfortunately not labeled) and to terminal H on the E/L Unit. I don't know what the E/L Unit is, and I'd like to find out what the unlabeled connector is. Anyone know?

Thanks

69trgt6

Hopefully someone out there has some advice for me... I'm still unable to get a code from the car. I have done the battery dissconnect, press brake pedal, reconnect battery thing. That gets the check engine light out, but it comes back on in less than an 1/8th of a mile and I'm back in limp home mode. I don't supose that anyone else has run into having a problem like this without being able to get any codes. I did find out that the E/L until is an electrical load Unit that is suposed to increase the engine RPM at an idle if it detects a high elerical load. Anyone on the board local to the Schenectady NY area?

Mahjik

iTrader: (1)

Here's a test for the E/L Unit:

If you don't have the FSM yes, you can grab it here:

http://www.wrex-racing.com/web/fd/info.htm

gracer7-rx7

iTrader: (16)

You might also want to test the harness that goes to the OMP. They fail or break sometimes and cause the OMP code to be thrown. OMP gets variable voltage depending on RPM and load

69trgt6

I'll check those both out...

Now, I'm wondering if anyone knows what the signal that is sent to the OMP is, and what the computer expects to see back, to let it know that the OMP is working. It looks like (from having dissassembled a bad OMP), that the stepper motor pushed a plunger to deliver oil, and that the plunger has a tab that hits a switch. Is that all it is? And the computer just wants to see the switch close at some frequency, increasing with engine RPM, to be happy that the OMP is working?

Anyway, Thanks for the suggestions, when the rain stops, I'll check things out more.

Greg

gracer7-rx7

iTrader: (16)

Its either voltage or ohms (resistance). I forget but the factory service manual will have the specs. It expects to see x amount at idle and y amount at WOT (wide open throttle). It follows a similar range as the TPS (throttle position sensor) iirc.

I don't think its open/close. Pretty sure of that.

Search for OMP as there are some good threads that go into details on this and have pics and all that good stuff. Something to do while its raining

cld1000

calling dale clark . . . calling dale clark. . .

69trgt6

OK, I've figured out a bunch of stuff on this car... The original OMP's stepper motor had failed, one half of each coil shorted out. The replacement Ohm's out good and the position switch does also. On the replacement, I noticed that the computer could not drive the stepper motor in either direction. Also, I wasn't able to get the computer to spit out any codes. This past weekend, when I moved the car in the driveway, the computer started spitting out all kinds of codes... While the engine was running... I recieved a stock computer that I bought off Ebay this morning and just installed it. The car ran good for about 15 minutes and then the check engine light came back on and it went into limp home mode. So, I thought I'd try the code thing on this computer and it actually worked. I'm getting 2 codes: 20 (Metering Oil Pump Position Sensor open or short circuit, and 27 (Metering Oil Pump Sensor open or short circuit or MOP sticking). The OMP's proving to be a real pain. Where do you get resonably priced replacements? I'm going to try and Ohm out the position switch again to see if it's bad...