I'm looking to buy an 1990 GXL FC and I have a question. I tried a search but I didn't find an answer to this specific question.

Anyways, the car starts up, runs fine, no leaks, puff of smoke on start up lasting about a second. Took a ride in the car, pulls through first just fine however, in 2nd gear at about ~3800 RPMs, the engine check light comes on, and the car goes into limp mode.

He says its probably one of the sensors, and its been like this for about 6 years, he doesn't drive it much, and since the car still ran he never bothered to take it to get repaired/replaced.

My question is, if hes been running it in limp mode for 6 years, is the engine going to be damaged or loose compression in any way? From reading on the forums I hear the most common cause of Limp mode on an S5 is the OMP, so I was wondering what if hes been running on a bad OMP for 6 years?

Hes owned the car for about 10 years, and hes only put about 12,000 miles on it giving the car about 113,000 total on the chassis. Everything is stock, the engine has never be rebuilt, and its been passing smog for all those 10 years.

Any kind of response wold be appreciated.


PS: Random facts that might help?

-If the car is turned off, the engine check turns off.
-The car starts in 2 to 4 cranks hot and cold.
-Oil pressure is fine?

 

it could be clogged secondary injectors, or bad grounds. tps could be bad or out of spec and needs to be readjusted.

have you check the fuel pump for how much pressure its putting out? is there any smell of gas in the car while its running? hows was the fuel economy when he drove it ? does it run good under 3.5 k rpms ? are the aux. ports working? what about the actuators for the ports are they working ? check and see if ALL the connections are plugged in!!!

 

Did not check the fuel pump, how does one do so?
Not an alarming smell, smells what most RX7s smell like.
Not sure, in first gear under 3.5k rpms is fine, when he shifts to 2nd, limp mode kicks in and he has to hold the throttle at the right position, any less or any more and it sorta stutters.
I didn't check the aux ports because the car never really went past 3.5K RPM. Ditto for the actuators.

I didn't check the connections either.

if the TPS was bad wouldn't the idle be flawed as well?

thanks for the response though.


PS I thought I would point out, limp mode doesnt ALWAYS kick in 2nd gear at 3.5 RPMs, sometimes he can get through it all the way to third, but it kicks in often. When engine check light is off and the car is not in limp mode, you can rev the engine pretty high, not sure how high, i wasnt looking at the tachometer

 

Well just check the codes. Go to ROTORWIKI (http://www.rotorwiki.com/index.php/89-91_Error_Codes ) and read how.

It's most likely the oil metering pump OMP which puts it in limp mode. OMP new cost more than the car is worth. Use? Got me.

http://www.mazdatrix.com/getprice.as...m=14-600B-N350

 

If hes been running on a bad OMP for 6 years, is the engine going to be damaged or anything?

 

Its a good possibility the engine has damage.

 

I would do a compression check

 

Okay, hes going to get the car fixed by his mechanic tommorrow. If the problem was a bad OMP, I'll run a compression check. however when he took it to the mechanic previously, he said it might have been one of the sensors.

If it is one of the sensors, would running on a bad sensor for 6 years damage the engine? I understand the things about carbon build up + aux ports freezing if you don't redline in a while, but I'm more concerned about compression and permanent damage to the engine.

thanks for all the responses.

 

It sounds exactly like a throttle position sensor issue. Either it's on its way out the door, is way out of adjustment, or has a loose connection. You can check it in 5 minutes with a multi-meter. My car has done the same thing with the tps settings wrong, and it would slightly affect the idle, but not much.

 

thanks, i'm just gonna sit tight till his mechanic fixes the car i guess, then I'm going to give it another test drive and once over.

 

Even if he fixes the problem and it runs I would still do a compression test just to get a good idea of the condition of the engine.

 

I would love to but I dont have any kind of compression tester. Would the poor man's compression test do?

 

No. Buy one, they are cheap. Just hold the needle in as it turns over.

 

yeah you can pick one up from advanced auto or sears for about $20. Just hold the check valve open while you have someone crank it. This will allow you to see the compression on all 3 faces of the rotor. The compression should read AT LEAST 80 psi.

 

on the S5 rx7s the top plunger on the tps is what tells the omp how much oil to put in the engine, therefore, if this is bad then it would put the car into limp mode as you explained, and also could damage the engine if it was getting the wrong amount of oil.

if it was the omp itself the car would be put into limp mode from start, if it is the stepper motor or tps then this would happen as you explained.

I have the same problem, im hoping tps, otherwise i have to buy the rteck 1.0 to stop it. (ive been running premix since i put the new engine in.)

also, check the omp and tps connectors. spray a little electrical connection cleaner in them and try that too. and on the top plunger of the tps.

 

Thanks for the advice guys. So anything under 80 PSI is a BAD motor? What would be an Awesome/Decent/Barely Passing Motor. Aaroncakes' buyer guide said 90 PSI is what you should look for so, im a bit confused. But thanks for the advice regardless.

 

A good motor would have right around 100psi.

 

K cool, I'm just waiting on his call now. Hopefully he gets back to me by this weekend.

 

good luck. let us know how it works out for you.

 

Or a bad starter

 

Just an update, but when he took it to get fixed, the codes threw a bad OMP, however he still hasnt gotten around to replacing it.

He said $3000 for the car with the bad OMP, and I'm not sure if hes ever gonna replace it himself, but if he were to it would cost $3,500.

I asked him about the Engine Compression and the oil pressure again to see if everything is okay, and I'm just waiting for a response. But I take it from the general consensus here, running on a Bad OMP for 6 years will cause the engine some damage.

 

He said fixing the OMP would raise the price to $3,500? You can buy a used omp on here for $50 and install it in about 10 minutes.

FYI- Unless you know the seller personally, I would not ask him what the compression is. I would check it myself. There is to a chance they would do it wrong or lie about the numbers.

Brian

 

Check your OMP

I had the same problem and it took me about 2 months to locate the problem and it was a bad OMP (Oil Metering Pump) Once I put in a good one, she now runs perfect!

 

Hmm, i see you what youre saying about testing my own compression, I was just thinking maybe he had compression numbers from Mazda, which would probably be more accurate. I'm pretty sure he wouldn't check the compression himself, but would have a mechanic, but I'm still waiting for his response anyway.


And i do realize bumping the price up by $500 for just an OMP is ridiculous, but that offer was made before he found out what the actual problem was. Now he might be able to go lower.