I found another 7 about an hour away from home. The body and inside are in really, really nice condition. The engine starts right up but it idles funny. It bounces between between 800 and 1000. The owner tells me that it is supposed to run like that because it has been ported.
The 7 is a 1990 T2. It has a RB 3 inch exhaust, RTek 1.8, 720 cc injectors and a fuel pump from a 3rd gen 7. No emissions. Its a 5 speed and supposedly has been rebuilt within the last 3 k miles.

Would the porting cause it to idle bad or is it just another bad idling 7?

ashley

 

TPS out of adjustment, vacuum leaks, timing off, bad plugs, etc .....Lots of things cause bad idles, however properly set up a street ported engine can run smoothly.

 

does it have a boost gauge? if so, what is the vacuum reading at idle. It should only lope badly at idle if it is a really extreme port, and more than likely it is something out of adjustment.

Are you in morgantown? I didn't think there were any more rx7 people here anymore...

 

Hi, it does have a boost gauge but the gauge just stays on zero while idling. The gauge quickly up to about 10 with brisk acceleration (not floored).

So, is this guy just giving me a bunch of BS?

I'm from Weirton, northern panhandle. I've been on here since my Dad bought me my first 7, for my 16th birthday, about 7 years ago. I've had 5 different 7s and I kept one for two years. I have a 1990 GXL/T2 swap that I've been trying to get on the road for 9 months.

thanks for the reply, ash

 

Is the boost gauge capable of reading vacuum? or is it a boost only gauge?

If it has a vacuum section then the supply line is connected to the incorrect vacuum port.

 

Hope you find the problem? It does sound like a tps adjustment issue or a leak past the throttle body possibly.

 

i would also assume the TPS. try unplugging it to see if the idle smooths out

 

Depending on the price, this could be a great deal with an easy fix.

 

Even very large street ports can idle perfectly smooth below 1,000rpm.

 

The present owner swears that it has idled like that since he had it rebuilt. He says he was told by the builder that it has an "aggressive street port".

The boost gauge is attached to the intercooler tubing right after the throttle body. Its connected to the tubing between the throttle body and the FMIC.

Another thing, it doesn't have a boost pop-off valve. He said that it wasn't needed.

I went to look at it again today. Its really, really nice and my favorite color - red. Of the five 7s that I've had so far, all five have been red.

Today he said the engine was just rebuilt within the last 500 miles. I thought yesterday that he said 3k miles.

 

i went and looked at a car a few weeks ago that the owner said the same thing. it was surging about 1000 rpm during idle. he said it was normal because it was a rotary and that they all did that. i unplugged the TPS and it smoothed right out. it's something simple to try and worth a shot.

agreed.

 

[/QUOTE]Today he said the engine was just rebuilt within the last 500 miles. I thought yesterday that he said 3k miles.[/QUOTE]

The owner might be full of it. Watch out.

 

When I was shopping around for rx-7's I found that for a lot of people "rebuilt" can mean anything, right down to "I changed the spark plugs".... so unless there are dated receipts don't believe a word of it.

 

possibly a frew things wrong with it that has been covered by others here. When you were driving it, did idle raise or drop when you put the car in gear but held the clutch pedal down? Any hissing sounds from the passenger side? Did you get to see the cold start (revs up to 3000 RPM for a little and then drops holds at about 1500 RPM)? Could be vacuum leak anywhere or even on the intake manifold itself.

 

That's why it doesn't register vacuum.

The bypass valve isn't "necessary" but it does prolong the life of the parts. Why do you think ALL turbo cars since the late 80s are equipped with them?

 

Where should it be hooked up? The S5T2 that I have now has the boost hooked up to about the same area.

 

When you were driving it, did idle raise or drop when you put the car in gear but held the clutch pedal down?
I didn't notice the idling changing at all by putting it in gear. Why would/wouldn't the idle change?

Any hissing sounds from the passenger side?
No, I didn't notice any hissing.

Did you get to see the cold start (revs up to 3000 RPM for a little and then drops holds at about 1500 RPM)?
It doesn't have the cold start rev to 3000. To keep it running when its cold you just have to give it a little gas for about 30 seconds. The owner said that is because he had the throttle body modified when he had the engine rebuilt.

 

^ Just some symptons of a bad TPS I was listing or a possible vacuum leak (hissing)

 

sounds like a cheap fix, but definitely bad tps.

 

It should be attached to the intake manifold. Its current location is basically cut-off when the throttle is closed or partially closed, and therefore it will not register vacuum, and it will read higher than actual boost. Only a moron would put it in this location, so that does not give me a warm and fuzzy feeling about the shop that rebuilt the engine.

A pop-off valve is an ancient method to limit boost. Some people still use it as a last-resort failsafe, but usually you only see a pop-off valve on race cars that require one due to racing rules. Most cars nowadays have a blow-off valve, which serves a completely different function.

In that case he should have no problem providing you with the receipt. Most decent shops have a 1-year warranty, so you should ask the shop if they will honor the warranty if you buy the car. They will also be able to tell you what kind of port they put on the engine, what exactly is new, and any problems that they know of.

 

Bouncing from 800-1000 doesn't sound like the tps. When my tps was out by a mere .20 volts it was jumping from 800 to 2500, back and fourth.