A low engine compression issue.

 

Obviously the A/T is less than desirable.

She didn't have this problem last year, so obviously something has gone amiss over the winter, but is it possible that it's a transmission issue ?

Ah, sorry didn't see the next page RR.

I was afraid of that. In other words, a possible apex or corner seal leak ?

 

It would make sense that the engine is under more load while in drive than it is in park or neutral so this could be your issue. I wouldn't go all freaky expecting that your engine needs rebuilding.

 

You need a certain level of compression to maintain a steady idle, especially under load. When the general wear level inside the engine (mostly apex seals vs rotor housings) drops to a certain point, the auto cars have a hard time idling under load of being in D. I have had auto cars brought to me that ran and drove fine except that they would stall almost anytime you tried to let it idle in D. A basic refresh/rebuild resolves this, since compression will be higher after break in of the rebuild and the engine is once again strong enough to maintain idle under load.

 

I don't want to continue this much further as we are kind of off -topic now and others will have a hard time finding this information.

However, the car has become harder to start and actually required the un-flooding procedure to get it started the last time. So I am thinking this points even more towards the Apex Seals ?

Thanks guys for all your help !!

 

I am unsure why this is so hard to understand. Compression is formed primarily by the seal between apex seals and rotor housing surfaces. Of course corner and side seals vs. iron walls also contribute, however those surfaces do not wear much at all compared to the apex/rotorhousing combo, so it is okay to leave them out of the discussion.

When one or both of those surfaces becomes worn unevenly, gaps develop and compression decreases slowly. At a certain threshold the weak compression begins to cause problems such as those you are encountering, although nothing has actually broken or catastrophically failed yet.

 

Not hard to understand at all RR, just making sure that my assumptions are correct.

 

The only good automatic transmission in my opinion is a Mercedes-Benz trans. I had a 300TE and it hauled *** when you stomped it. It always was in the right gear climbing a hill.

 

Thanks for thread & the comments Tidge.. I was actually looking for a Auto convertible for my girlfriend. But now kinda scarred to buy one :-(

 

IF she's not lazy or technologically challenged, get her an 89-91 with the hold feature and tell her to drive it in manual mode. It's not that bad when you do that, assuming that

1) you actually have a decent auto transmission

and

2) you have an engine still with good enough compression that startup and idle difficulties are not concerns.

 

Tell her to man up and learn how to drive a manual transmission...

 

You are Correct... we both love the S5 style convertibles... I almost bought a blue 90 with 95k ($3500 obo)but when i get there, it was sitting at a shop, passenger side carpet pulled up.
(wished I didnt seen that) talk to the head mechanic.. 3800 hesitation (omp).. I offered him 1500$. No deal & I walked away. I guess we will stay in market for a AT S5

 

3800 rpm hesitation is not related to the OMP, but more of a grounding, secondary injector issue.

 

Well, I don't know that I would be scared of them as last year the car ran perfectly. She has a Honda Accord that is 5 speed , so she wanted an auto.

As RR said if you find one with decent transmission and good combustion it really is ALMOST as much fun as the 5 speed.

 

I have a clean 100% stock brave blue 91 vert with a rebuilt engine and rebuilt auto trans that I'd sell if that's what you really want. Everything works, has a rebuilt wiper switch and idiot cluster, the a/c has been gone through, it's been daily driven for a year since I built it. It needs a top but I have a new in box top to go onto it (just no time to actually do the job). Body is perfectly straight, even has a turbo II hood (I also have an NA aluminum hood that could be swapped), but does need painted due to a poor previous repaint.

 

just picked up an auto fc... too slow and not fun. looking for 5 spd swap already

 

This post needs to be archieved. I just picked up a S5 NA 1990 auto with 56k miles, did a compression test, the motor shows 100+psi on both rotors all 3 faces. It does exactly everything RR mentioned. the car skips gear like crazy, it stalls in netural, reverse and drive. Basically I have to keep my foot on gas pedal the whole time to prevent it from stalling (this is my first auto RX7 and I had a hard time using both feet driving). Once it stalls, ill have a hard time starting it back up. One more thing is, everytime I floor or rev it past 3000rpm in neutral, the car temp will reach the red zone. I need a couple advises here.

 

Rebuild the engine. The overheating problem is separate from the rest. It is a failure that will become more advanced as you drive it and eventually you will not be able to restart the engine or take trips longer than a few miles before it overheats. Make plans for secondary transportation now.

 

Its not losing any antifreeze though. Would it be some kinda blockage causing the problem?

 

The cause could possibly be a bad thermostat, a bad clutch fan, or a corroded radiator.

But, none of that really matters once you've made a trip or two to H on the gauge, because by the time the needle starts to move from the middle to the top it's already at 240+ and you've probably damaged one or more coolant seals. So even if you fix the external problem that may have been causing the overheat, the engine will never be right again (unless you're extremely lucky, or unless you're exaggerating about how hot it got).

 

I found out the car has wrong plugs, plug tips have rust and the car was running on water instead of coolant...... Also when I crank the motor, it splits a couple drops of water off the plug holes. Looks like rebuild time for me...

 

Ask yourself...why would a car have water/rust in the cooling system instead of antifreeze/water mix? After all, most owners are too lazy to actually flush/change their coolant, so most cars with an original engine should still have the original coolant in it.

Because over time it has been burning/pushing the antifreeze out due to a long term coolant seal issue, and the owner has been replacing it with water alone.

I can spot a coolant seal engine a mile away. Anytime you walk up to a car and find water in the cooling system with nearly no antifreeze, RTV all over the water pump and thermostat neck, a replacement radiator, a replacement coolant cap, a replacement upper radiator hose, and a trail of white or brown deposits coming from the thermostat neck and/or radiator fill neck, that's a dead giveaway that the engine has been having major coolant and overheating issues for a year or more and the owner has been trying to fix and/or bandaid it.

 

I picked up the car literally 4 days ago. Im going flush the system today then put in some 50/50 and see how it holds up. But hey thanks for the help RR