Multiplex

Hope someone can point me in the right direction with this one because I am lost.

From time to time my RX7 will stop at 4000rpm in 4th gear and not go any faster. It just looses power and that's it.

After a little while, usually after going over some rougher road it suddenly works again and I have no problem pulling it to 7000+ rpm.

This is a standard 1987 RX7-FC

SpeedRacer

Hmmm....sounds kinda like 3800rpm hesitation, only much worse. Well, just in case you can try cleaning your negative battery terminal, and tightening it, as well as adding a thick ground wire from your negative battery terminal to your chassis.

Multiplex

Hmm, I've heard about this, but I'm not sure if this is the same as my problem.

Here it really just stops at 4000 rpm, just asif it is limited. Also it seems to have less power going to 4000 rpm, it's like only one of the rotors is still running....

Anyways, I'll see if it helps just in case...

HAILERS

Completly lost here. I think you should go to the ECU and disconnect each plug and reseat it. Then follow the engine harness from the ecu and you'll find a major disconnect in the upper passenger side of the interior. I'd disconnect and reseat it after looking for major flaws.Same withe mass air flow meter plug and the boost sensor, tps plug and the water thermo plug on the water pump housing. Its more than just losing the secondary injectors because I know you can reach 6000-7000 without them if you ease thru the 3800 barrier. On the ECU you should check the ground wires on each of the plugs. If you have no manual go to the net and download the fac manual, section 4a or 4b and the wiring diagrams. Section 4a or 4b will show the ECU plugs and what each does in life i.e. the grounds. If I get any real thoughts on this I'll write back. Only 4000? Can't creep up to 6000?

Six Rotors

iTrader: (17)

Hey Hailers,I checked a car a few weeks ago which had similar symptoms to this.After putting the engine signal monitor on the car I found a secondary fuel injector dead.There was no way the car would run more than 4000rpm and it also sounded like it was running on 1 rotor(it was!).You can demonstrate this to yourself by disconnecting a secondary injector and driving your car--it's a different sensation and sound to the 3800 hesitation.My guess is this car has a bad wire/connector on a secondary fuel injector circuit.

HAILERS

Six Rotors.... yeah I did something like that a while back. I took both secondary plugs off and went for a ride. I'd step on it and when the rpm hit 3800 I was thrown forward in the seat, could say violently. I found that if I eased the car thru the 3800 I could get it up to 6000 or so. Well worth looking into the condition of the injector plug wires. They get brittle which means just at the injector plug the two wires can touch if the plug has degraded enough. Could take the plugs off and put a meter with the leads on both and with the meter on ohms , wiggle the plug to see if they dead short out.

Multiplex

Indeed, it just stops at 4000 rpm, it's impossible to go above that. I've driven like that for something like a minute.

Strangest thing is that after a little while it suddenly works again, so my guess is either some loose wiring or maybe something to do with heat (it's been pretty hot here lately)?

Anyways, I've got plenty to look at this weekend, so I'll let you guys know what I find:-)

Thanks!

SpeedRacer

Maybe your is running in limp mode when this happens. Have you checked your engine codes yet?

Multiplex

Hmm, I haven't checked it the after last time but it was checked earlier when we already had these problems. I don't think it gave any problems but could be wrong.

Anyways, it's going back to the garage this weekend and we'll see what we can find then:-)

Keith

OK, in the last post F1EBRU said he had a failure with his OMP causing this problem. Your car is an '87, with a mechanical OMP. The ECU knows nothing about it. Also, he mentions reading out the ECU error codes. Uh, you have an '87, with a very basic ECU. You have no check engine light to read out error codes. Even if you did, the ECU does not have a memory to hold error codes. So, if the failure is not occuring right at the point you read out the codes, the ECU has forgotten it, and you will read out nothing! You may be thinking now "the way he is talking, there must be a way to read out error codes". You are right! If you get some 12V LED's, you can read out error codes as they happen, via a 4-wire test connector located near the driver's side strut tower (not to far from the leading coil). I have this set up on my '87, and am using the engine monitor pin as a minimal A/F ratio meter. The wiring diagram is at 2ndrx7.freeservers.com/techmaster.html. Select reading error codes and the details to build a readout device and the few error codes available (there are only a little more then 10) will be displayed. I say all this in the hopes that the ECU will spit out an error code when the failure is occuring, and you will then be able to see it. Good luck!

Irv, Keith's dad

Multiplex

Hmmm, sounds interesting. Was it the board computer giving an (false?) error message that caused the car to go into limp mode or was there really something wrong with the pump?

If my '87 has a much simpler computer it may not be the problem I am having, or there might be another error signal causing the problem.

BTW, Irv, I can't get to the site, is that URL valid? Also the error code readout, can that be mounted so it can be viewed while driving? If the error code disappaires after the engine runs okay again then I probably won't see it because most of the time this problem happens while driving.

Thanks! Seems we got loads to do this weekend:-)

Bigmike

I had the exact same problem, but in every gear!

the word HAD is the best part

Re-do all engine grounds, just for fun and to be safe ... ie. battery, 2 on engine, boost sensor ground. But the one thing that fixed my problem was one of the clips for the secondary injectors was loose! , just put it back on properly and all fixed. Make sure no other connections are loose, or corroded.

hopefully this works for you too,
goodluck

Bigmike

Multiplex

Hi Irv,

Like I said, the URL http://2ndrx7.freeservers.com/techmaster.html does not seem to work:-(

Bas

HAILERS

Try this url.. http://home.rmci.net/panther/ecu_codes.htm

Keith

Whoops! replace 2ndrx7 with 2ndgenrx7, the link should work. Here is the complete link. http://2ndgenrx7.freeservers.com/techmaster.html Sorry about that! In my '87, I drilled a few holes in a plastic panel just below the stereo, installed my LED's in it, and then wired it through the firewall to the test connector. I also used the monitor output to go to a third LED on the panel, so I would have a rudimentary A/F ratio monitor also. I know it works, because every time I start the car warm, it gives me a code 05 (Oxygen sensor) until the sensor warms up. The ECU thinks that on a warm engine, the O2 sensor should also be warm (anything after a few minutes and it's not, of course). This is one sharp ECU here!
At any rate, if your problem is being caused by the ECU, you should see an error code while driving. Lemme know if you have any further questions.

Irv, Keith's dad

HAILERS

Sorry, I'm hyper today...try this one also..........http://www.teamfc3s.org/main.shtml The ecu codes is under Articles. That team fc3s.org has a lot of information, but I only seem to be able to access the things I want by going to the *old site*.