Boost problem......
 

I was finally able to do the 3rd gear boost test on my car yesterday since buying it over the winter. I had my friend sit passenger to tell my my readings and here is how it went. On the highway I get into 3rd gear .. around 3500 rpms im hitting 10psi all the way up to 4500rpm. Right after the boost drops to a steady 4psi from 4600 rpm to 7000 rpm. So I immediately think the car is in need of the good ol' vacuum line fix!! I call a-spec tuning and set up a appointment. So im on here just to make sure that my assumptions are correct and that I dont have any other underlieing problems?

PS. Car is a 93 R1, fully stock, 53k on the ODO. Only things I have done are change out the plugs, wires, coolant flush and oil and filter change.

It depends what you mean by underlying issue.

The turbos are almost certainly fine. It's possible that a solenoid, actuator, check valve, or reservoir tank are bad. (These are the things the vacuum hoses connect). So if your vacuum hoses were fine, and you replace them, the problem will remain. However, during this hose job is the best time to replace the problem.

If a-spec has some background working with the stock turbo control system (many rotary shops don't) they should be able to make a good guess as to the problem by doing a couple hourse of troubleshooting. It may be a simple solenoid replacement or popped hose, in which case it's your call whether it's time for the vacuum hose job as well.

Dave

edit in boldface

Just curious how/why you make that assumption. It sounds like he has next to nothing boost-wise after transition.

Bad secondary turbo? Or does the fact that primary boost disappears also suggest a stuck wastegate perhaps?

Very common problem, most likely you have an issue with your pre-control lines/solenoid or a check valve.

Try to pull the codes off the computer. It takes like 2 seconds and maybe it will show a shot turbo control solenoid or something that the shop can fix at the same time as the vac lines.

When I say the turbo is fine, I mean that boost levels don't indicate the need to rebuild/replace them.

Turbos spin in air. Unless there is a mechanical problem with them (which results in grinding sounds/noise), or there is oil leakage, there isn't much else to worry about within the turbo unit. Maybe I'm missing something in this case, but 95%+ of the time it's the dozens of components which control the airflow to the turbos causing the boost problems. At 52k, solenoids are getting tired (esp. the turbo control pressure solenoid) and the hoses tend to embrittle and pop loose.

Dave

Ok, thanks for all the replies. I was just making sure that I there wasn't a larger problem at hand. I'll update after my appointment in the shop.

Well I got the car back from A-spec tuning last friday and here is the update. They said I had 2 solenoids that needed replacing and they did the whole vacuum line replacement with silicone ones. Here is the bad part, they took the car back out on a test drive to see if it did the 10-8-10 pattern and the first turbo spooled fine but the second turbo after transition only peaked at 7psi. I spoke to the shop owner and he said that my pre-cat may be beginning to be clogged which is hindering the second turbo from fully reaching 10 psi and that a downpipe would fix that problem. Is this correct?

If you have more than 40,000 miles on your car and the original precat, I'd say they are probably right. Have them dump the precat and put in a downpipe. It will run about $500 labor and material but it is the best investment you can make for your car.

It sounds reasonable. Pre-cats definitely definitely fail or clog.

Dave

Update 5/31/05
 

Well I got the downpipe in last week and it still turns out that the car is having the same secondary turbo boost of 7psi... after another day of troubleshooting it at the shop, turns out that my wastegate actuator rod was bent! So finally my boost issues are fixed.

Thanks to all that helped

:bigthumb:

heh, I had a very similar thing happen to me, only the rod was somehow disconnected instead of just bent. Congrats on getting it fixed!

Currently im having the same problem and im woking on it !!!!!

good luck with fixing your problem!!