themonsterisme

iTrader: (2)

so a couple of days ago i noticed my factory blowoff valve was disconected...(i had heard it blowing louder than normal) and i hooked it back up. she normally boosts at 12 lbs with no problems. well tonight i was dropping off my friend with benifits and noticed it was boosting up to 12 then jumping to 15 and dropping to 12 then 14......wtf? i also noticed earlier today it seemed she had a miss...well it seemed like she ran a little rough like she was missing a little and was running god awfully rich....any ideas guys?
(by the way...everything is stock other than 3 inch donwpipe and cat back 3 inch racing pipes FYI) could fouled plugs be the problem? but it didnt seem to miss much tonight though....im stummped

Rotary4tw

iTrader: (3)

My first question would be how does it sound at idle, etc? Does the vaccumm gauge bounce around at idle, and seem to struggle at lower RPM's?

I know not everybody has access to a nice rotary compression tester, but if you know somebody who has one, try to get the car comp tested as soon as possible. It takes about 20 mins and it really is the best starting place.

I lost a seal this summer, and had some strange boost issues as well. After the compression was shot, and I boosted really hard (had a new engine, was not concerned about the old one) I was seeing some crazy bouncing manifold pressures. I would fly around between 14-18 psi and my boost gauge would have incredible play in it. This was with a blown engine mind you.

If there is a compression issue with your car, it may be spiking in a simmilar way. Also, I was not seeing fuel cut, or anything else when it was getting up to 18psi. (I am not exagerating one bit. At first I thought the guage was off, but it's a mechanical system... if the guage shows it... it's seeing 18psi, right?)

This was really confusing because I figured that the turbines were smashed from the seal, and would be incapable of making that kind of power, but when I inspected them last night (we pulled the engine) they were intact with no bent or missing fins... spung like a champ.

So in summary, I would try a compression test. When the seals are compromised and you boost, you can see some crazy manifold pressures under full boost.

Good luck, and I hope it's something much more minor then overboostage.

Also... 12 pounds of boost is not normal for a stock car, and how were you determining that the car was running rich? The stumbling could have been fuel cut (around 14 psi I think?) but I'm not sure how long that would cause the car to stumble. If you have poor compression, the car will run incredibly rich, because there is alot of unburnt gas. I got horrible fuel mileage for the last few weeks and could smell gas when the turbo's were on.

Compression test.

-Rotary4tw

themonsterisme

iTrader: (2)

well...it ran kinda rough...not bad...but like a slight miss at idle...but at a higher rpm it ran fine....at idle sometimes it doesnt register on the gauge but sometimes its saying lean...very lean...but i asked my sister and she says hers does that sometimes(she has a pettit motor) the car gets jerky when the 2nd turbo kicks in and at high rpms...like 8000 it cuts out so i dont go that high cause im afraid of killing it by doing that too often with the whole lean thing at cut out.
it didnt seem to miss at all when i took her home tonight...just overboosted like crazy...and it didnt do it everytime ....i dunno...
so you might think its commpression?

themonsterisme

iTrader: (2)

oh yea...i determined it was running rich cause i have a air fuel gauge...and there was only stumbleing at low rpms.im not quite sure why its running 12 lbs...pettit seemed to think it was cause of the exaugst....told me not to worry bout it...when i got the car i was freaking out cause of my oil pressure gauge going crazy on me and my sister called pettit and asked bout that and the 12 lbs of boost....her car didnt do it cause she has the upgraded oiling system on her car.....they said it was ok and fd's sometimes show crazy readings...this is what she told me they said....i dunno...sigh

Rotary4tw

iTrader: (3)

Do you know if it's a narrow band or a wide band o2 sensor?

If it's a narrow band, basically just a gauge from 0-20 that hangs out in the middle most of the time, it's probably only running off of 1 volt, and will only give you an accurate reading unless you are under WOT.

You probably want to lay off boosting until you figure out whats wrong, you can lose your engine at 14psi no problem.

"FD's sometimes show crazy readings"

Well, a boost gauge is mechanical, meaning when you see 15psi, you are seeing 15psi. 15psi is not good at all, especially on the stock eqquipment.

Here is a simple way to see if you have lost compression on the car. (Even easier then listening for the psshts in each chamber)

Start the car, let it idle.
Look at your boost gauge, and look at the vaccuum.
Is it constant, or is it bouncing between different values?

If it's bouncing you have some sort of issue, either compression loss or a vaccuum leak in one of the hoses.

From there, you need to try to figure out why it's over boosting. We would need to know what all of your mods are etc.

Do you have any friends in the area that own an Rx-7, or a shop, that could help you out? Do you live near Pettit?

Btw, when your engine "cuts out" I think that may be fuel cut. That's no good, you have to be really careful if you are running those kinds of boost levels.

Do what you can to lay off the boost until you get the the boost issue resolved.

-Rotary4tw

themonsterisme

iTrader: (2)

im about a hour and a half from pettit and i was going to drop it off in the next 3 or 4 weeks to have them rebuild the motor since its got about 76500 miles on it.the only mods i have are cat back 3 inch racing exaugst and a 3 inch down pipe, boost gauge, and o2/fuel gauge, apexi intakes.
i guess i just wont drive it hard untill i can figure out my boost issues. not sure on the o2 sensor either.

dgeesaman

iTrader: (7)

Unplug the electrical connectors from precontrol and wastegate solenoids - that should keep things under 8psi. You will definitely need to get this sorted out.

Dave