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fiix me before my owner pulls the rest of his hair out

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gzfqy6:
Ok so clearly I do not have the knowledge or especially the patience for these challenges anymore, but at least I have a friendship base & other resources who are more auto-intellectually inclined & emotionally balanced for all the failures required before success.  I am afraid I have lost my patience in throwing parts at this car & more than happy to let someone else tell me what to try next.  So here is the dilemma……………

1984 Mazda Rx7 GSL_SE in stock tune.  That includes the stock EFI, fuel delivery, ignition, emissions (less cat. & AIR pump).

History: This car has been driven 2005-current on the road and at the track without issue…..well of course until now  :).  This April drove all the way to Gingerman with no issue.  First 20 minute session on track engine had no issue.  Second session on track after a couple laps the engine would not rev past 5500rpm.  No missing or quitting just would not rev…… kind of like a piston engine equipped with a cam profile not engineered for high revs.  Since it was starting & running fine otherwise I packed up to come home.  After traveling around 120mi having no issues I went to start from a traffic light and the car would not run with a load….. Idled fine, but would not pull away.  There seemed to be missing, but no nasty backfiring or anything.  Had car towed home.  Once home the car started and ran fine as I went for a short drive & parked it in the garage.  Replaced coils since it is a cheap/easy thing to do and drove the car several days to work spirited as I could, but certainly not in the way you would at the track…… no issues.

Before leaving for Grattan Memorial weekend I went ahead and put on the distributor from another engine that had no issues just because I could and it is a lot easier in my garage than at the track.  Left Friday afternoon in horrible conditions….. 90deg’s, on & off traffic jams…. No issues.  I was pretty encouraged that it made it there with no problems, but realized that until proven on the track it really didn’t mean anything other than heat & distance alone were not factors.  Saturday first 20 minute session no issues.  Second session after a couple laps, same as Gingerman…………. Would not rev past 5500rpm.  Packed up to come home & this time after around 60mi right on the highway it started surging & losing power.  Happened to be in a safe area to pull over and not knowing if it would conk out in a worse area I went ahead and called a tow (which is a story in itself I’ll share someday).   Once home (finely) same as before, started and drove around a little before putting in garage.  Fuel pressure and volume checked fine although I don’t know what good that is since of course it is when it is running ok.

I do have another ECU I can put in, but of course it is used without history….. oh wait the seller said it came out of a running car so I know it is good   ;).  What I really want is one of you well seasoned individuals to tell me exactly what’s wrong and save me a bunch of aggravation.  So throw me all of your 10 cents worth of hypothesis, I’m game.  The problem is that it only acts up after being run at the track….. and only after the second session at that.

~Groll69~:
Sounds like your fuel pump might be starting to go out.  Also might want to check the wires near the ECU to make sure none are starting to wear and short out.  I have an 84 gsl-se in my driveway that the wires for the fuel pump under the carpet by the ECU had worn melted and began shorting there.  (there were two shorts on the car and that was just one of them)  My guess is the fuel pump is starting to wear our and the heat from it running is cuasing it to begin to fail.  Since it is an external fuel pump, there is nothing to keep it cool other then air.

gzfqy6:
lol.... if that is the issue it will be another one of those "if it ain't broke, don't fix it" lessons.  I put a new pump in a couple years ago thinking that 30 year old pump should probably be replaced (even though it never failed).  I'll go ahead and put a pressure gage inline on the car so I can at least see whats going on when it starts acting up.  These things ain't no 65' Chevy when it comes to throwing parts at them.  Fuel pump $350, TPS $220, filter $40....... yikes $$$$$$$$$$$$

Thanks again for any input.  So far since initial post.......... verified clean tank & screen, fuel filter, added some engine grounds, verified TPS adjustment and checked all connections.

~Groll69~:
For the fuel pump, you may be able to go through rockauto for some cheaper options.  they do supply us with a code for 5% off of your order too.  If you still have the original pump, you can see about re-installing it and see if it takes away the issue.

gzfqy6:
As I go through to check & verify various components hoping I get lucky in stumbling across whatever is wrong with this thing I observed this: Timing is dead on, TPS verified yet car will not idle at 800rpm (never has).  750rpm is the most I can get.  Adjustments to the air adjustment screw & idle mixture will only decrease rpm not increase it.  Never cared because the car has always run perfectly (and still does till it starts doing what I described in my original post), but now that I am having this intermittent problem it just made me wonder if something is going on that I should know about.  Is there any mechanical means (a screw for butterfly opening) on these goofy things or is the idle all the ECU & air/fuel ratio?  I really doubt this has anything to do with the problems I am having, but it just seems that if the manual says adjust the idle to 800rpm I should be able to.

................. you know, I never have checked the plugs.  Maybe I need a colder plug for the track... any opinions?

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