93 rx7 wont boost past 5 lbs
 

A couple of days ago I drove my car and the boost would not go past 5 lbs it would fall on its face completly, but it wouldnt die(seems electronical) As long as I do not pass 5 pounds of boost it runs perfect. When I do go to 5 lbs it back fires pretty big and it throws out a fire ball. then today I took it out and it worked fine. then I washed it and put coolant in it. then the problem started again. the motor is warn but it does not smoke starts fine and idles perfect. I only have a down pipe mid pipe and a catback exhaust and intake on it. other than that it is stock. what could it be??

Vacuum lines, probably. Don't ask me which one.

With a midpipe installed you really need an ECU upgrade or you will blow your motor...

about a year ago I had all of the vaccum lines replaced my a-spec tuning. today I was checking them couldn't find any bad ones. I took the car to about 50 miles per hour and put it in 2nd and bearly got on it to see how the boost reacted. it started hessitating really bad and around 1 or 2 lbs of boost. could it be the fuel injectors are stuck?

This is not the sort of problem stuck fuel injectors could cause.

if the secondary fuel injectors were stuck what would it do? I forgot to mention that this all started after the winter I started it 3 times during the winter time. before winter it ran perfect. then a week ago I tried to drive it and it did it. if that can help any? what are something I should check. please I need help

does anyone know were I can get a stock mid pipe at for a good price?

Faulty injectors means flooding, hard starting, bad fuel economy, fuel smell. Obviously with your fireball-shooting you are getting way too much fuel but something other than the injectors has to be at fault. And, that certainly wouldn't cause hesitation. But I'm not really a 3rd gen guy, so my ability to figure out exactly what it IS, is pretty limited.

As for a stock main cat, I'd recommend the local forsale forum, FDs are emissions exempt in Chicago AFAIK due to age, so you can probably get one for cheap. You'll need your air pump hooked up, as well.

I am having this exact same problem! Boost will quickly rise to 5 psi or so then cut out.. Any help would be greatly appreciated..

I was told to use a propane tank to check the vaccum lines is that a good idea? if so were would I start?????

Im having the same problem. Just blew my high-flow cat to hell yesterday with a huge backfire...flames, smoke and chunks of honeycomb. hehehe I would think its vacuum related but I have replaced 95% of the lines under the motor. No difference in the problem. So I guess its time for the other 5.

* Propane is ok for finding a vacuum leak, but that's the sort of vacuum leak that makes your idle suck. The FD turbo control plumbing doesn't have vacuum all the time. Unless it's a hose that has vacuum at idle propane won't find it.

* There's more to the rat's nest than just hoses - there are also solenoids, check valves, and maybe other stuff too that can all go bad. I know a lot of times people put check valves in backwards and then stuff won't work. So if your lines look ok... look closer!

There are a number of things that will not allow your FD to boost proberly. Here is a quick run down of things to check. Turbos, controll valve, controll sylinoides (cant spell this early sorry), check vavles, IC leak, and make sure your gauge works its rare but it happens.

Also check to see if your 2nd turbo is coming online and how much oil is being leaked internally and externally.

same problem but I am getting 5lb clean
 

and then an ignition break under boost. When I disconnect my intercooler pipe car is clean to redline as an NA motor. I am think new plug wires as I have seen this once b4. New plugs and no vacc leaks what so ever. 3" dp md and cat and apexi intake. Friend have the same setup and is runnign 12-14psi on stock ecu.
I want the same but I will add a PFC as soon as i get it to run clean as is..

Anyone tried the igniter I am going to try that next since I have an extea then to wires. after that the coils.

Lots of times when boost is stuck at a steady 5psi it's the double throttle hose. See if that came off.

Good luck :)

ps actually sense this problem is on and off that might not be it but it could be the solenoid

where it the Double trottle hose located?
 

My problem is only under boost and pops at 4-5 psi. Cr drop great whe i took it in for winter storage. I have all new plugs wires fuel filter all vac lines look good.

drive it NA and redline w/o a problem.
Took the plugs back off and the trainling looks kinda wet. So I will swap out my igniter next and boost sensor after that.

its easy, vaccuum leak ,...somewhere. Sometimes the primary fuel rail can cause this. I DO KNOW if you continue to let it pop like that you'll be singing "pop the magic rotary" song.

I've have never worked on a fd, but low boost + backfire sounds like boost leak to me. Is it possible to use a compressor to check for boost leaks or do the check valves prevent that?

Well I have new plugs and wires on the way. They are three maybe four years old but the car was not used for almost more than a year when i had it in school and painted it. so hopefully that is the problem. how can I tell if i do have a boost leak?? how would the car act?

get an air compressor, and a bottle of soapy water. Pressureize the intake system, listen for leaks. Soapy water bubbles around a leak.

i had the same problem when i just bought mine. I noticed that the two nuts that hold the bottom part of the compression tube were missing so it wasnt getting a tight seal. Once I put two new ones on there it boosted to 15 psi no problem. Might not apply to you but it was the only change I did and it fixed it immediately.

Today I changed the plugs on it. It ran smoother but still cut out the same. I dont think I mentioned that when I am in first and I keep the boost at around 0-1 psi i can let it rev to redline. no problem but if I let the boost go any higher it starts popping and putting and if i open it up it will hit 5-7 psi and fall on its face hard and back fire really loud. but even if i have the boost steady at 4psi at 4500 rpms it will stutter and put alot but the boost stays consistant. could that be a boost leak since the boost stays consistant like that?

My car I took it out today i was at 4500 rpms stepped on it enough to make the boost reach 3 psi held it for a sec it hessitated then the boost dropped a tiny bit under 0 went smooth till it built boost back up. I am pretty sure it is a boost leak...Any thoughts on were I should start to look for a leak or a easy way to look for leaks? please help!

If I were to use the air compressor were can I connect it to? and how? to pressureize the intake system?

Can anyone help me? is there a way I can pressureize the intake system?

Near the bottom of the page:
http://www.fighters-garage.com/rx7.html

I changed 3 out of the 4 check valves today and swapped out the charge relief valve and the bov with used ones also. I still have the same problem. i changed the 3 check valves that are by the pressure tank. the one under the uim I didn't change I was told that it would not cause boost problems. And I had a venting hose to the crv that was cracked I got a new one. Any Ideas on what else I should check?

Did you even test any of the solenoids on the rack?

no i didnt. how do I check them?

Ok, let's start first with the issues with the car. If you do a pull from 3rd gear, what does the boost pattern look like? What happens to the car and at what rpm does it happen?

well pretty much if i hit 5 lbs or higher boost it falls on its face. and if i keep it at under 5 lbs boost like at around 3 or 4 it will go fine until i am around 3 rpms it will start hessitating pretty bad.

You have verified you have no ECU codes?

Most likely, either the car is going into limp mode, or you have an issue with your ignition or fuel system. Have you thought about taking your car to: http://www.a-spectuning.com/ ?

no i have not verified that I have no ecu codes. How can I verify that? I have no check engine light that comes on. As long as I dont make the car boost high it will go to red line no problem. And I was also wondering on how I can reset the ecu?

I'm not trying to be an ass or anything, but those are basic things you can easily find out by using the forum and the Factory Service Manual (which is available as a download).


Use the FAQ thread as it has links to most of your questions:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/

Download the FSM (Factory Service Manual):
https://www.rx7club.com/3rd-gen-archives-73/tech-manual-directory-614824/

There are troubleshooting guides in the FSM. Lastly, use and search the 3rd Gen section:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/

You have a 3rd Gen RX7, that's where you should be looking for information.

I pulled the codes by using the diagnostics box it gave me 2 codes 23 and 51. that is the fuel thermosensor and the fuel pump relay. So should I get new sensors or used? what would be my best step in this situation?

Us the FSM. Page F-110 has procedures for testing the Fuel Pump Relay.

Page F-40 has steps for the Fuel Thermosensor.

my car wouldnt do past 5 pounds once and it was the cat it calapsed and failed on me

His problem is that he has two codes which both will throw the car into limp mode.

I have a straight pipe. So that cat wouldn't be my problem. But about the limp mode after my car falls on its face right afterwards the exhuast tone kinda changes for a sec and response in acceleration is a lot less so I think that is the limp mode. I am gonna bring a multi meter from school tommorrow and test the two sensors.

Can anyone tell me exactly what the fuel thermosensor and the fuel pump relay do? I have an idea but I want to be sure!

Rex wont boost over 0.2bar
 

My car wont boost beyond 0.2bar. Everything seems fine, rats nest re piped. Reaches 0.2 wont go higher, at 4600rpm the big turbo comes on, takes the 0.2 but no rise in boost at all. No dips. Anybody got any ideas??