non sequential turbo lag help

[turboholic]

Hey guys,

Im trying to run tech support from afghanistan on my new car. Rangers old rx7.

My brother made this video for me showing how much lag there is in 1st gear. It looks like 6 or 7 psi at 5500 rpms. I read that with non sequential mod that you will have lag but it should see full boost by 3800-4000rpm.

Poor mans non sequential.

Any ideas on why there is so much lag.

http://www.streetfire.net/video/rx7-non-sequential-lagging-issue_2379785.htm


Thanks.
Nick

[chickenwafer]

First thing I would do is go "Rich Man's Non Sequential". The car is already setup to do it, it just takes some elbow grease to accomplish it. Remove the butterfly in the y-pipe, the door in the exhaust manifold and the turbo and put a bolt and nut thru the hole to seal it shut, plus the secondary BOV if it's not already done, and I think that's basically it.

What is boost peaking at and when (it's hard to sell the boost gauge in the video)?

If boost never gets above 6-7psi you are probably missing the pills in the w/g line. They are small restrictors that limit the amount of air to the w/g actuator to allow you to run the full 10psi. Without these you will see less boost. This is the first thing I could check. You can also always get a MBC and control boost that way; much better than swapping/dealing with the pills IMO. The pills are in the reference vacuum line right off the primary turbo compressor outlet and run down to the w/g actuator, pretty easy to spot.

If the pills are in place but boost is still low, I would start looking for a boost leak. The y-pipe coupler is a notorious spot for a leak where the y-pipe and crossover pipe connect (unless you have a '99 spec y-pipe, which fixes the issue with a 2-bolt flange connection). Other possible leak points would be around the intercooler or the throttle body elbow since it uses an o-ring gasket. Also, check the factory BOV and it's connection. The valves don't typically leak, but they are connected with a rubber hose that crack and fail.

Lastly, you should also check how the Poor man's non-seq mod was done. Make sure one of the doors hasn't become un-wired and fallen shut or something.

[Ranger]

Hmm, I'm pretty sure it was making a constant 10 PSI the last time I drove it (before your brother looked at it obviously since the boost gauge wasn't hooked up at the time). So I think it should be something simple.

If boost never gets above 6-7psi you are probably missing the pills in the w/g line. They are small restrictors that limit the amount of air to the w/g actuator to allow you to run the full 10psi. Without these you will see less boost. This is the first thing I could check. You can also always get a MBC and control boost that way; much better than swapping/dealing with the pills IMO. The pills are in the reference vacuum line right off the primary turbo compressor outlet and run down to the w/g actuator, pretty easy to spot.

If the pills are in place but boost is still low, I would start looking for a boost leak. The y-pipe coupler is a notorious spot for a leak where the y-pipe and crossover pipe connect (unless you have a '99 spec y-pipe, which fixes the issue with a 2-bolt flange connection). Other possible leak points would be around the intercooler or the throttle body elbow since it uses an o-ring gasket. Also, check the factory BOV and it's connection. The valves don't typically leak, but they are connected with a rubber hose that crack and fail.

Lastly, you should also check how the Poor man's non-seq mod was done. Make sure one of the doors hasn't become un-wired and fallen shut or something.

From what I remember of the gauge it does look like about 6-7 PSI. There is a manual boost controller in the glovebox, it's a red line running through the firewall on the passenger side. When I got the car, it was hooked up and set to run 12 PSI max when it was sequential (so 12-10-12 instead of the factory 10-8-10). Does that mean the pills were most likely removed? I didn't hook it back up because I was told it probably wasn't necessary, and I wasn't sure where it should be hooked up anyway.

As for the y-pipe, IIRC it has an Efini one. Is that the same thing?

Also, Nick, if you're interested, I should have the number of the guy who helped me do the non-sequential conversion. That was a long time ago but I'm sure he'd be willing to help out if he can. The main reason I went non-sequential is because the car had boost issues after I got it back from Precision, and I liked the feeling of his car, which is non-sequential.

[chickenwafer]

Normally people do remove the pills when installing any form of aftermarket boost control, but, you never know. A lot of people don't know they're even in there so they never check or remove them.

Yes, Efini y-pipe is the 99 spec y-pipe, same piece. It flows better and replaced the failure-prone coupler joint at the crossover pipe so it's a good upgrade.

[turboholic]

Thanks for the input guys. Im going to keep troubleshooting and see what I come up with.

[Ranger]

Normally people do remove the pills when installing any form of aftermarket boost control, but, you never know. A lot of people don't know they're even in there so they never check or remove them.

That is most likely the problem then. The boost controller was installed by Rotorsports Racing out in NC, which I hear is a pretty competent shop, so I'm sure they would've removed them. They installed the PFC too and did the 12-10-12 tune.

[chickenwafer]

Well if Rotorsports installed the boost controlled, I bet they removed the pills. If no one has adjusted the MBC and/or the boost control function setting in the PFC, then there really is no reason it would be getting the full boost is supposed to.

That would make me thing it's a boost leak, if nothing else has changed the lowered boost just happened all of a sudden, out of the blue.

We had a similar issue when I was tuning Dan's white FD, we couldn't get it above 5-6psi (his car was still sequential), even when I turned the w/g actuator solenoids completely shut in the PFC! Turned out the y-pipe coupler (and something else, I think) was leaking really badly.