So I'm out in my FD on a Saturday night, when...
 

As you know I haven't had my FD long and at about 8:00 tonight my wife comes to me and says our 2 year old son needs cough medicine and my 9 week old son needs baby formula....doesn't take a guy long to run to the garage and let the ol'7 warmup. So this is like my first Saturday night ride in the FD and GEE FREAKING WHIZ! Every damn Import, Mustang, TransAm and Z28 in sight wants to race. I kept my cool and just let them wonder whether or not they could take a FD...for some of them you've gotta believe it was there first time to even see a FD (Neareast one to mine is in Huntsville, AL=60 miles away) Anyway, like I said I kept my cool until these 2 guys in a about a 2000 model TransAm just wouldn't leave it alone. So from a third gear roll-on it was, "so-long little birdie." Then guy wants more and this is where it began sucking...

I'm in 2nd gear and everything is great, turbo spins up, BOV goes "phish" changing into 3rd and then...I hear no spin-up of the turbo...I have major boost lag going on...4,500rpm and like 5psi and then 6,000 rpm it shoots to about 13psi. I let of gas and BOV goes "phish" (as normal), come to redlight, idle is good at 900rpm...so I shift into neutral and WOT I get 5psi, so that seemed fine. Light turns green and everything is fine shifting through 4 gears. I ride around for a minute and everything still appears fine. Then I get on it one more time and 1st and 2nd are fine and then...boost lag again in 3rd. I go home and look everything over and everything seems fine. Then I notice that one hose on my HKS Super Megaflow was very very soft. The hose is pictured below. Could this hose be collapsing and causing my problem? Any help would be great...thanks - Brad

https://www.rx7club.com/attachment.p...hmentid=166020

pic no workie

Try this attachment then...thanks.

Those 2 hoses are where the bov and crv vent back into the intake...it's pressure being vented. They have nothing to do with boost being generated in the first place. So no, that would not be your problem.

try the couplers leading from the intercooler down to you y pipe. i was only boosting about 5 psi through all the gears until i found my leak. i think the best way to find a leak is with the engine on and pulling the throttle so you can hear it.

Sounds like a classic case of boost leak.

I hear you are excellent with the mechanics of the FD. So do you have any guesses what my problem(s) is?


I have the Efini Y-Pipe so I'm assuming those are ok.

About a week ago the bottom Intercooler hose poped off when I hit 3rd. I took it home then and put a fresh clamp on it and tightened up. I took it off again tonight just to check and put it back on and drove around. Everything is fine until the motor starts to really warmup good and then I get boost lag in 3rd...I can down shift into 2nd and then shift back into 3rd and everything is fine again....it's pretty annoying.

so its more like hesitation? kinda sorta? what other mods do you have?

Yes, sorta like hesitation but I can't hear the turbo "whiz" and even though I'm still getting boost, I can tell the power is way down.

Some will have nothing to do with my problem but:

HKS Super Megaflow Intake
Silicone Lines
Efini Y-Pipe
Racing Beat Dual Tip Catback
Pettit Racing Boost Gauge
Pettit AST
C-Short-throw Shift Kit

No Downpipe or midpipe.

I have a HKS PFC F-Con that is still sitting in the box.

That's it I think.

i'd keep checking for a leak somewhere, check the coupler that attaches to your y pipe. mine popped off about 2 weeks ago and i finally had the time and will power to actually stand over my car find it. its probably something simple and you will kick yourself, and punch your head repeating "stupid, stupid, stupid, stupid"

/\ Yea, you're probably right. I appreciate your help. It's my night to stay up for the 3AM bottle feeding of my 9 week old, so I guess I'll be in the garage until then. :(

also, check the spark plugs, guys had hesitation and changed them out and that got rid of the problem

Will do.

let me know how it goes and happy hunting :D

What about gasket condition between UIM and block. I believe I read somewhere that these are possible blowout points?

Also, isn't a Megaflo + no downpipe + no midpipe + RB Catback with no fuel control system a bit risky?

LOL, off-topic, but this reminds me of the time when my teenage daughter was riding with me and the same thing happened. Following a couple of others, a guy in a older but obviously modded mustang just wouldn't stop. He followed along side for what seemed like forever. I'm busy trying to ignore the kid and I hear my daughter start laughing so hard she can't talk. When I look over she'd taken my ID case out of the glovebox and was holding my badge up while pointing at me. He made the the next turn. :)

If you get full boost in some gears, you do not have a leak. You have a problem in your system that is failing to actuate your boost all the time. Weekends are not usually the best time to get good advice here :D.

check valve could have poped off in the system...go digging.

I suspect a loose vac hose connection, check valve failure, or maybe a bad solenoid.

Unfortunately I can't be more specific until you start verifying these items.

Dave

BINGO!!!:icon_tup:
Dave helped me fix mine, same problem only in first and second. Only 5 lbs boost says failed actuator, check valve, or solenoid. I am betting on the solenoid. I had a charge relief valve that was bad and two solenoids. You have to pull them out and test them hot and cold. Its confusing sometimes too. I fortunately got it down. I fixed my problem. Good luck. If you want info on how I did it just PM me. Goodluck, I am sure Dave can help too.:icon_tup: BTW, congrats on the baby, I have a month old son. Life is good when you have children. Take care.

Yea, I know what you mean...I'm a cop too. I guess I broke the law a little last night playing with that TransAm but I guess every once and while is ok.

And before anybody says, "hey man that's not right because you would write someone a ticket for doing that..." I'm not a patrolman guys, so I DON'T WRITE TICKETS!

Still can't find the problem. Would it be a good idea then to just go ahead and replace all 3 since they are prone to failure? My FD only has 27,500 original miles on it and to my knowledge on the history of the car, things have always worked just fine. Honestly, I'll be a little harder on this FD than the previous owner who didn't have time for it and only put 13,000 miles on it in the past 9 years, so I guess things will start failing a little at a time with me because I'll actually drive the thing.. A LOT! :)

God damn finally some bood info from some senior members. Damn noobs need to stop posting and start reading. Last time Ive checked if you have a boost leak there is no way in hell your gonna get 13psi...Ever!!

I've read everything that I care to read... 3rd Gen Faq, fd3s.net, about 50 different threads before I even posted. I can't say that I've read the first one where someone is getting boost and everything is just fine and then you're not getting boost in one gear and then you downshift and you've got boost again. I know there have been plenty of guys on here that have had that problem but a person can only read thru so much bullcrap before they just want to talk to people "computer to computer" :) and have direct answers from those who care to answer.

Some of you guys are like old cops that don't want to help out the rookies. Instead of showing them the ropes you let them just figure out things on their own and you end up with crooked, arrested or dead cops....In other words, try helping newbie FD owners or they'll be a lot of torn up, blown FDs in the future and you guys that know everything about the FDs can have forum where you can talk to each other about, "Remember that newbie guy who didn't know what was on page P-7 section 131.2 subsection A of the Shop Manual? Man that guy was an idiot." :MissileSm

Boost leaks can be pretty unpredictable. Look for them anyway.

Usually the let-off throttle to get full boost indicates a leak in the vacuum system, which is recharged when you let off and create manifold vacuum. After running the car, shut off the engine. Reach in beside the alternator with a set of long pliers and pull the hose from the plastic tank buried down there. (That's the vacuum tank). You should hear a bunch of air hiss into the tank and hose. If not, it's definitely leaky.

A bad check valve is one source for leaks, but a loose vacuum hose is another. Only careful inspection and removal of some stuff will find it. If you have a vacuum pump (borrow the one from Autozone, or buy one) then tee that into the vacuum chamber and use the pump to draw air - this should make the leak hiss. I'm not a fan of using carb cleaner, but if you start the engine, whent he carb cleaner is sprayed on the leak the engine idle will surge.

After 13 years, the rubber in the car isn't what it used to be. If you decide to change solenoids, I'd suggest changing the turbo control vacuum, turbo control pressure, charge control, and charge relief solenoids. Also install new check valves.

Dave