NewRXr

I passed both of my 7's onto my sons as their first cars but I still lurk around and occasionally make a meet. My boys still have the cars and my 19 year old still daily drives his '86 NA. I'm an ASE Master Tech and do very well with diagnosing problems but I would like to run some symptoms by you all in hopes of a faster diagnosis since these cars are so old and good information is hard to find. I spent some time searching but didn't find it.

It's an '86 coupe, NA, 5-speed w/ 190K.
The car has been run ragged over the last 4 years 50K with teen driver and it's a few months away from retirement. It's been a champ after I did all the preventative maint. and as many pre-emptive repairs I could as I was getting it ready for him when I used to drive it.

Today on his lunch break it started normally but the coolant buzzer was going off so he shut it off and topped off the coolant. It was noon and about 50* and sunny out.
When he tried to restart it seems to have flooded. 2nd time recently. He called me and I walked him through the fuse pull and dry out procedure that he watched me do a few weeks ago. It started up but was running really bad like a severe ignition misfire or blown apex seal. Many misfires and backfires. He works a about 1.5 miles away from my shop so I convinced him to bring it over and take my truck back to work.

We he arrived he said it was running smoother but the tach was still inop. When I got to it 4 hours later it started right up but was running rough again. I started pulling the spark cables off the coils one at a time and all the coils were producing great sparks. I started wiggling the wires on the trailing ignitor and the idle would react pretty hard some times so I checked the tach and now it was working. I checked the connector on both ignitors for fit and corrosion etc. but all seemed in order. I couldn't get the wires to cause a reaction every time. It seemed to be smoothing out again and so I drove it and it started running and idling normally again.

I went to his job and shut it off for a couple minutes and decided to take it back to my shop. It started rough and was idling like crap again. But I blipped the throttle and it revved roughly and then just smoothed out until I got back and shut it off. Now at every warm start it repeats, crap then rev and smooth.

I pulled the trailing plugs and they were not fouled but I cleaned them up and put them back. Tach still working, even when it's running like crap.

We were closing up and he was back so he took it home for the night and I'm trying to figure out where to start.

Has anyone dealt with this that can tell me what you found?

Thanks,
Vernon

Silverfc88

iTrader: (7)

Any smoke at startup?

AGreen

iTrader: (11)

I seem to remember something about that when I used the stock ECU on my 88 convertible. If I pulled the EGI fuse and cranked the car, the subsequent startup would run the entire time with no tachometer. If I disconnected the negative battery cable and reconnected it, the tachometer would work. I guess you could say it reset the coil pack/ignitor (it is a pack of transistors after all). I stopped using the EGI fuse and ended up disconnecting the crank angle sensor. It's just as easy, and won't give you the erratic tachometer.

It sounds like you're experiencing a couple things: Maybe the compression is a little low on the engine, which only aggravates the flooding issue worse. Short starting (i.e. starting cold then shutting off before fully warming up the engine) will flood the engine. Another good possibility is that you have leaky injectors, which is all too common on these old cars. An on-car injector service won't take care of that either. I used the BG injector service kit on mine at my old shop, then a few months later sent them to witchhunter performance to have them cleaned and flow tested. The results were astounding. I thought I was a believer in the on-car injector flush until that. No matter what, you can't get rid of the sediment in the strainer.

Anyways, the point is that if you have leaky injectors, it'll definitely make the car run shitty on startup, then get better as it heats up and burns off the excess fuel.

I'm sure you know how to check leaky injectors (ziptie them to the fuel rails, jumper the fuel pump), but the compression test is a little different for a rotary. Here's a good link:
Banzai Racing Compression Test

NewRXr

Thanks for the advice.
It does smoke on start-up a little but always has since I bought it at 125K. After finding a tip on here and Changing to Texaco Havoline it reduced that to liveable, just a second or two. I'm sure the engine is well worn at this point and I'm sure compression is getting low. I'm just glad the apex seals have held up to him this long. I didn't know about the tach being inop on the first start after pulling the EFI fuse but it makes sense because it's been working since then.

He made it to work this morning so come lunch I'll find out how it ran and if it's still out of wack I'll get him to leave it again. I'll try the compression check, I'm familiar. This is my third RX-7 and all of them were cheap because of fixer-up issues. But this is my only FC, my other son has my old GSL-SE and I spent a lot of time getting that fuel injection to work right but it still had the distributor. It's possible that an injector is leaking, I can't remember what I did to these if anything. I replaced the SE set and I know I replaced the regulator and damper on them both but I can't remember if I did anything with these. I had read in a few places that you shouldn't do an on car injector flush to a Rotary Engine so I doubt I did that. If you have without hurting anything it's certainly an option for me to do now. I only need to keep her going for a few more months.

Thanks again, your time is appreciated.
Vernon