Most probable cause(s) of bogging at boost..?
 

Recent history...

Installed primary/secondary injectors,..complete silicone vacuum hose job. New plugs, new battery.

The car starts up great cold. AWS kicks in,..comes off, and engine purrs in idle as it should. The car is an Auto. No abnormal idle or engine noises are notable. Everything sounds and feels normal .

Problem begins while driving. The car runs very good until I try to accelerate. As the car begins to approach ("0") boost, it bogs and sometimes backfires. Absolutely no boost is obtainable.

The Primary Turbo has a nice spool pitch, so I don't believe it's a turbo issue.

What would you guys rule-out first before tearing it down again?

Thanks for any help and assistance.

I'm guessing severely torn boost coupler or other major boost leak. That's the #1 cause of absolutely no boost. Depending on exactly how the leak and pressure loss occurs, it could be fooling the ECU and causing the bog.

On the other hand, it may be a fuel-supply problem. If the fuel filter is blocked, the fuel pump is bad, or there is a voltage-supply problem to the pump, there may not be enough fuel to support any boost.

How long since the filter was changed?

Dave

Did you check for codes?

Might be your charge control valve (code 45).

Thanks for your input Dave.

I'll check the voltage at the FP. I guess anything less than 12V would not be good. New battery should be delivering well though. What about not enough Amps coming out of the Alternator?

As far as the Fuel Filter, I took ownership in 2003 and since then have only run the car about 11K miles. Not sure if the FF has ever been replaced. Perhaps a good time now.



Haven't yet. How reliable and accurate is the diagnosis? Is this done by KOKO and counting the flashes? BTW, my check Engine Light has not come on. Only warning light flashing is the ABS.

Thanks for your help.

Yes "counting flashes", connect the GND and TEN terminals with a paper clip, and check whether it shows code 45 "solenoid valve - charge control".

Eeech. I'm afraid when I went thru the same symptoms I was having secondary injector problems.

A boost leak would not tend to cause bogging and backfiring. Fuel injection troubles would.

Any chance you could test the AFRs with a wideband?

Dave

i can almost guaranty your problem is fuel related... It sounds as though your getting more fuel than the car can handle when you enter boost... I know this because i had the same symptoms while trying to tune my microtech for when the secondary injectors come on...when they came on, they were throwing too much fuel into the engine for combustion... this would also explain the backfire...you are getting unburned fuel in the exhaust which is hot and causes the fuel to ignite in the exhaust.

Okay.,.sounds pretty logical.

So apparently the Secondary Injectors fire-up as soon as Boost is obtained, regardless of engine RPM ? If so, then are the SI's stuck in wide-open position or being prematurely [electronically] opened at boost?

FYI, the SI's (and PI's) were cleaned and flow tested by Witchhunter a few months ago before the install took place.

Thanks for your help!

Maybe it's time to do the drummers injector treatment.
https://www.rx7club.com/showthread.p...=injector+drum

Dave

Thanks Dave. That's one of the threads that came up when I did a search on Injectors. But with my luck, this method of solving my issues would probably just be a temporary fix, so I've decided to order two new secondary injectors from Ray.

Although, I do intend to first check each S.I. for proper activation (clicking) with a hot wire. If I get no clicking, it will be very obvious that they were the culprit.

Just to recap, once the injector is grounded, a "click" should be heard when the hot wire touches the other terminal ~ meaning that the injector has "opened"....correct?

If the injector does not click, this would indicate the injector is stuck in an open position?

I'll probably take them out during the week.

I don't really know how to tell if an injector is stuck open or closed without trying to figure on the AFRs. But if you don't get a click when you apply voltage you know you have a problem.

IMHO, there's no hack with this method. The injectors are clean and they aren't well lubricated with fuel yet. Once you get them clicking they should operate nicely for a long time. Since you already paid to have them cleaned, it would be worthwhile to at least wait to buy new ones.

Dave

Fair enough Dave. If I get them working (clicking) well., I'll reinstall them and take her out for a test drive.

I'll come back with follow-up.

Thanks for your advise and guidance!

Bogging/Backfiring
 

I had another thread going similar to this about how my car would cut out at 7 psi. If the RPM's were high it would take less boost (1-4psi). I just replaced every vacuum line on the car today and it made my problem worse. I can no longer get boost.

I now have the same problem that you have. Every time my car approaches boost it just bogs and will backfire if I get on the throttle harder than granny does. My car has a new fuel filter so it is not the FF.

My car hasn't run properly since I bought it three weeks ago so hopefully you and I both can figure it out. I know my MAP sensor is good and in proper working condition. My TPS is also accurate.

This thread may be a bit helpful. https://www.rx7club.com/showthread.p...=injector+drum
I am looking for every solution to this problem as this is my daily driver and having no power sucks.

EDIT: My o2 sensor wire just broke off, so maybe that is a issue?

I suggest resetting your ECU also if you haven't done so. It is done by disconnecting your battery for 15 seconds.

it sounds like you forgot to tighten a worm clamp on your boost side pipes.

https://www.rx7club.com/showthread.p...%2A+boost+bogs

I faced a similar problem and it seems a few others have as well. Was just making a suggestion since checking for codes only take a couple of minutes. You can easily rule out one possibility.

Thanks for the heads-up on the post.

Did you get your issues resolved? If so, what was the problem?

Thanks again.

If you have them out of the car, it's entirely reasonable to install them in the rail, pressurize the lines, and use the ECU and main relay terminals to test each one.

Dave

Hello Dave,

I really didn't want to take the Rail off, but if that's the only way (run the test with seconday fuel assembly intact) to positively confirm proper Injector function, I'll do it.

I figured I'd just pull the Secondary Injectors off [leave the Rail on] and manipulate the SI's with a hot wire.

Thanks again.

In that case just leave them in and pull the UIM. When they click it's pretty easy to hear. But then you'll need to unflood the engine when you're done.

Dave

There you go!.......... :)

Although your'e probably aware, don't forget that for safety sake it helps to make the connection for the test away from the fuel lines and injectors and stuff. 12v isn't always powerful, but it makes nice sparks, and fuel vapor likes that. In your case the fuel should be in the engine, but it pays to be safe.

I ran a wire from the ecu terminal over to the egi relay, and connected my battery to the wire over near the EGI relay.

Dave