rickdar

All help and comments welcomed!

Quickly,

When I take out my trusty 85 GSL and get on a highway (only time I've noticed) and get up to ~60mph @ ~4,000 rpms in 5th, it starts to kick and "miss". It will do this for about 5 mins &/or 5 miles and then kind of get ok and then drive fine.

Scoop:

123,000 Miles
pretty much stock.
Racing beat muffler
replaced pre cat
gutted main cat
Just replaced fuel filter
plugs are about 20K (going to replace this weekend)
wires/cap are about 45k old

This was similiar to a couple years ago when I figured out my main cat was plugged. I gutted it and then it ran just fine. But, at that time it would start to die and would never recover. This is very similiar to when a fuel filter gets plugged, but I just changed it!

It seems to be related to not being completed warmed up, however, I have tested this when the choke has kicked of and is "warm".

I have not replaced any vaccum hoses since buying at 76K either.

Before surrendering to the dreaded auto mechanic shop, I want to do all that I can myself, especially with the help of other RX7 fans.

Unfortunately, I just moved to Oklahoma City too, and I don't know a good RX7 mechanic here!

Well guys, any suggestions?

Thanks.

-Rick

eddierotary

iTrader: (7)

ok mine use to do that. i recomend to check the pos cable and the neg cable. sometime is loose or worn. i tell you because happen one time to me the car start fine but after you start moving start miss firing. another thing is check the gas line too. the metal and the rubber ones. check too the cap and rotor and wires.

DONNA

how old is your accelerator pump, might be cracked and loosing pump pressure,,,

hanman

First, I don't recommend revving your car too high when it is cold. Not wise with a rotary. Second, has it been happening when it is cold? Possible carb icing. Have you run the car real close to empty lately?
hanman

MarkPerez

you've bought new plugs,right ? what do the old ones
look like ? remember where each one came from,leading,
trailing,,what rotor ,1,,2,,

rickdar

Just an update and answer to questions:

-Haven't run close to empty lately
-This afternoon, I let it idle to warm and then sprayed some carb cleaner in and then went to Pep Boys to get plugs, wires, and caps. It didn't act up at all!
-Checked as best I could all the vaccum lines. They seemed to be fine and solid.

I will put all the new stuff on tomorrow and report back.

Just a question, If the pre-cat was starting to plug, wouldn't it consistently drive like crap all the time. This seems to be inconsistent and again only when "cold"

Thanks for the posts so far.

Keaponlaffen

Kinda off-topic, but I was just wondering, what is the recommended highest RPMs that you should rev a cold RX-7 to? 3500? 3000? I'm just going to take mine for a "real" drive (out of the school parking lot) in a bit, so I was wondering what I should keep it under for the first 10 or so minutes. My car gets heat (blower inside the car) really fast, so I'm assuming that when the heater caore puts out good heat, it's warm? Thanks.

Jeff

MarkPerez

The pre cats,or monolith cats are so close to the exhaust
manifold / engine, that they get wiped out from the
sheer heat that the rotory engines pump out.the main
cat is the only one I would fuss about..my 2 cents

rotorhead

i've always seen 4000 rpm is max on a cold rx-7. however, i tend to keep it around 3000-3500. personally, i'd wait until the temp gauge is at least 1/8" above the C mark before i'd go stomping on the gas.

Pele

iTrader: (28)

4000 RPM MAX, ANY ENGINE WHILE COLD!!!

You will damage any engine with an improper warmup or stressing it while it's cold.

Rotaries have the alternating sandwich of iron and aluminium housings which expand differently.

Boingers have the iron block and an aluminium head. All Aluminum engines must ahve some form of steel in them, be it a cylinder sleeve or something. I don't think aluminum would hold up to the wear or compression.

Being that the choke gets you to 2000 or more RPM and you need a power band to go anywhere, 4000 RPM should be good max.

If trannies had closer gearing, I'd prefer lower RPM till it was warm.. Once it's warm, it's a free for all to redline.