charliegt

Yes, you can remove it and use a multimeter to test the resistance. I assume you're talking about the fuel thermosensor that is located on the secondary fuel rail.

It should be 2.2-2.7 kohms at 68 degrees F (roughly room temp)

and

0.29-0.35 kohms at 176 degrees F

I used a trouble/shop light to heat it up and one of those digital fork thermometers that you use to check the middle of slabs of meat to check to see if it was hot enough. The hotter it gets, the lower the reading should be - so if you can't quite get it to 176 just take into account that your reading may be a little high.

You can find the complete instructions in the factory service manual, in the Fuel and Emissions Control System section - page F-170

:::::

UPDATE:

Just an update: all three thermosensors are ohming to spec. I pulled the fuel rails and although I didn't see fuel leaking out when the lines were pressurized, the primary injectors were wet on the tips, and the secondaries were bone dry. I went ahead and mailed them out to Witch Hunter Performance for cleaning today.

The more I think the problem over, the more that I'm convinced it is a leaky injector. It is really the only thing that would explain why my engine was flooded so badly after replacing the FPR (I think running the pump numerous times to check the pressure resulted in fuel leaking into the engine).

I also think that the AWS is functioning correctly (I tested the control valve and it works fien), but not revving up to 3k due to excessive fuel in the motor during startup.

Anyway, I'll have a few days before I get my injectors back so if anyone else can thinik of other things to check while I have the UIM and rats nest out - I'm open to suggestions.

Thanks,
-Charlie


-Charlie

Retserof

iTrader: (1)

Charlie, do you know offhand if any of the 3 thermosensors can be tested in place?

DaveW

I am no injector expert, but...
Bench testing should mean that they were tested to see whether they function properly (open, close, flow properly when open, seal when closed). How carefully they checked and whether something has subsequently happened to them is the question.

tcb100

Since we are throwing out ideas, an EGR solenoid stuck open would cause difficulties starting and make for a rough idle.

charliegt

You could test them at the lower temp in place, and I guess that would at least tell you that they are working 50% - but there really isn't any way to test any of them without taking things apart (especially the fuel thermosensor). Your best bet is to remove them, and once you actually get to them, taking them out is easy. I just used a 3/4" deepwell socket and it was able to fit over the plastic without breaking it. I used a 3/4" wrench for the coolant thermosensor.

Good luck.

-Charlie

charliegt

I just got off the phone with Witch Hunter (injector services) and they told me that my injectors were NOT leaking and checked out ok.

Is it possible that an injector would leak sometimes and not other times? I was almost positive that an injector was leaking.

Here is a rundown of my problem:

It started as a problem with hot starts. Car would act flooded and I would have to apply throttle for the first 30 seconds or so to keep it from stalling. Then, it would run fine. It has gotten progressively worse, now it happens during cold starts and hot starts - and almost every time. It still runs fine after the first minute or so, but I have noticed on my a/f gauge that it is running rich - and someone that drove behind me mentioned that my exhaust smelled strongly of gas.

I have replaced the FPR, and the spark plugs and checked the fuel thermosensor, the air intake thermosensor, and the coolant thermosensor. The MAP sensor is hooked up.

Right now, I can't think of anything else to replace/check (I have the rats nest out). So, I'm going to replace all of the vacuum hoses and the plug wires - install the freshly cleaned injectors and give it a shot. If anyone can think of something else to check while everything is taken apart, please let me know.

Thanks,
-Charlie

dgeesaman

iTrader: (7)

Have you check your TPS readings? Sometimes that will slide out of spec for no apparent reason.

Dave

charliegt

No, I haven't checked the TPS voltage. In the factory manual it says that the car needs to be warmed up, so I guess I'll wait until I put it back together and then check that - is there a way to do it without running the car?

-Charlie

dgeesaman

iTrader: (7)

Yes, turn the ignition on and make the adjustment while rotating the throttle by hand. I think it's even safe to unbolt the TB from the UIM to make the TPS more accessible. I haven't had the chance yet to double-check this with the car running, but others have done it without issue.

Dave

RotaryResurrection

iTrader: (8)

Sounds to me like you might want to do a compression check. Having ungodly amounts of unburned fuel out the exhaust is a sure sign of low/no compression in some part of the engine. Comp. check is the first rule of rotary troubleshooting.

www.rotaryresurrection.com ---> tech ---> compression check

lopedl

iTrader: (1)

I had a stuck side seal once that caused a lot of raw fuel to exit the housings. Someone told me you can rev the **** out of it and sometimes the seal will reseat itself. Don't know if thats true or not I just ended up rebuilding the engine.

BoostedFd3s

iTrader: (3)

i agree with doing a compression check....i went thru a similar problem....it was because i had blown apex seals on one of my rotors....

Rx-7Addict

iTrader: (2)

i would certainly do a compression check. Those are 3 strong symptoms of low compression (flooding, hard starts, rough idle).

Is it rough throughout the rev range, or just at idle? Best to check compression first and you can then test other things.

Mahjik

iTrader: (1)

(Merged original thread with the new one)

charliegt

It is only rough at idle for the first 30 seconds or so, and only some of the time. After that it idles perfectally and runs great (other than the rich condition - but my only indication of that is my a/f gauge, the person that drove behind me, and poor fuel economy).

I plan on doing a compression test tomorrow once I put it all back together.

-Charlie

charliegt

Compression test showed 90 on 3 rear faces and 95 on front faces.

I should also mention that I replaced the water temp sensor (it threw the code one day for a second) and it ran perfect for about a month. The a/f gauge was back to fluttering all over at idle and it started perfect every time. Then, all of the symptoms came back again (rich a/f at idle, hard hot starts and rough cold starts).

Thinking the water temp sensor could have gone bad again I replaced it but it did not fix anything. Both times I used a cheap Wells one from Autozone, perhaps the first one failed and the second one was faulty? I was also thinking there could be a problem with the wiring to the sensor, but wouldn't a short cause the ECU to throw a code?

The first time I ever had trouble starting the car was last April when I shut it down after pulling it out of the garage without letting it warm up all the way (it flooded). Ever since then I've been having problems with hot starts off and on.

This is really getting on my nerves, I'm about to just break down and buy a PFC commander so that I can see what signals the ECU is getting from the various sensors.

-Charlie

DaveW

This post by a3dcadman has some interesting info that may apply:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/rough-idle-dies-running-hot-odd-smell-hard-starting-sound-byte-attached-480478/

dgeesaman

iTrader: (7)

Bad, shorted, etc wiring can drive a person nuts with these problems. (I know, I finally rid mine by replacing the emission (main) wiring harness. Everytime I went into that area to check/fix something, I think it made the electrical problem worse. Of course, none of the problems could be detected using a multimeter - very frustrating.

Dave

charliegt

Thanks for the replies guys.


I've been following this thread for a while. It seems like a3dcadman's problem is a leak somewhere - I don't experience any strange fumes from under the hood. However, I am planning on looking into the EGR system soon.


Is there a part of the service manual that gives correct volt or resistance readings for the different wires at the ECU plug? I have a multimeter, but so far the only way that I've seen to test the sensors is to plug in to them with the multimeter.

-Charlie

dgeesaman

iTrader: (7)

FSM page F-147.

Dave

charliegt

Thanks! I can't believe I didn't see that before, that is going to help out a lot! On Wednesday I should have some time to go through and check all of the sensor readings.

-Charlie