DavidZ

I've been trying to troubleshoot a primary boost problem with little success. I only get about 1 psi of boost and cannot rev my engine any higher than 4000-5000 rpm when driving. Revs fine with no load.

I've replaced all hoses, replace a few bad check valves, and all IC couplers are tight and crack free. Done visual inspection of turbo and primary spins freely at idle, only little shaft play.

Could my problem be a bad coil? If so, how should i go about testing it? Any help or suggestions greatly appreciated!

spooledUP7

Yes, it could be your leading coil.

To properly test the leading coil (Not the spark plug wire to the ground bolt test) you need to have a quality ohm meeter.

Measure the resistance between the leading coil's harness plug poles (Primary coil). It should be below 1 ohm.

Measure the resistance between the two output plugs (Secondary Coil). It should be 9.6-16K ohms.

Also measure the resistance of your plug wires. They should be 16K per 3.28 ft

Keep an eye out for a bubble formed on the sides of the leading coil. That is a sure sign that your coil is toast.

Did you happen to mess with the throttle posistion sensor? If your sensor is out of range you could get the same effect.

Take a look at your pluggs, if the leading plugs are wet, then you may have a problem with your coil.

Double check all connections. Reset your ECU by pulling the EGI fuse (Or the negative battery cable) for a few minutes and pushing on the brake for a few seconds. Let the car go through a complete warm up and shut the car off. Then do it again. Then take it for a ride. This will reteach the ECU.

DavidZ

Thanks! Will try it out and post results!

Texas7

I would say no. When my leading coil went bad, boost would build to whatever I set my max to, but car would stop accelerating. I am also trying to diagnose a no boost problem that sounds similar to yours, and I have checked the following:

TPS: in spec.
MAP: in spec.
All solinoids: in spec.
Check valves all good.
All vacuum lines checked with no kinks.
Fuel pressure: in spec.
Fuel regulator: in spec.
Injectors: replaced.
ECU checked for codes and none found.

I currently have the solinoid rack out of the car after checking everything out and will replace it tomorrow. I had it out (of course) when I did my injector swap and after putting everything back together, it ran perfect. The next day, it was back to its old tricks. I thought a vacuum line was getting kinked after it got hot, so that is why I pulled it again to trim a few lines so they made more gentle bends. Hopefully, this works otherwise the only thing left are the turbos.

Mike N.

Texas7

Forgot to add, my car will rev to redline as long as I stay in vacuum. No matter what rpm I enter boost, the car falls on its face. Sounds like we have the same problem.

Mike N.

spooledUP7

Texas, I was speaking only from experience with my car. I had similar issues which turned out to be my leading coil.

If you would like to look at the turbo possibilities here is what you should look for.

I would love to take credit for this, but here is a good source of information to help you guys out.

http://home.istar.ca/~dvandit/TurboT...shooting.shtml

DavidZ

spooledup- You didn't mention if you checked your coils when they were warm?

texas- sure does could like a very similar problem. Wondering if you have considered a clogged cat/precat? If the coils check out ok, i'm thinking i'll try gutting the main cat.

Texas7

Spooledup, don't take my reply as a flame, I was only putting out my opinion just like you were. Just to rule my coil out, I also checked it and it is good. (Should be, it only has 1500 miles on it as does my engine).

Davd, I am not running any cats.

Mike N.

Texas7

Well guys, I think I found it. I rechecked all the solinoids, this time throwing them in a 200 degree oven to see how they worked when hot. The turbo control solinoid does not flow air when hot. When cold it works. Now there are two turbo control solinoids, one in the rack and the one mounted on the ACV assembly. It is the one mounted on the ACV assembly that is bad. (I hope).

Mike N.

DavidZ

Texas: by installing downpipe, o2 sensor and resetting ecu, i fixed my boost problem. I am almost certain that it was because my ecu was in in safety mode.

Not sure if you've reset youir ecu yet or not, but when i checked it for codes it did not show any codes either.

If you need solenoids, i know a guy who has tons of solenoids to sell.

spooledUP7

Texas, I think that you are correct in your diagnostics. The result of that solenoid not working when hot would be, (slow)poor to no secondary boost.
Since the Turbo Control uses both vacuum, and Pressure to actuate the the Turbo Control actuator, the malfuntioning solenoid would not allow any boost to occure if you did not make primary boost of at least 7-8psi.

Your primary turbo could be the result of the precat. Just look at david and his downpipe.

Texas7

I ordered a new solinoid when I discovered the problem, thanks anyways, David.

Spooledup, I haven't listed my mods because of the RX-7 car thief we had terrorizing Houston, but mine is a highly modded car, so the precat has been history for 3 years. Thanks for the help.

Mike N.

P.S. The solinoid was only $43 new.