Hey guys,
My car has been acting like a turd lately and I have a question.Sometimes when I mash the throttle my engine bogs down abit,almost the same bog you would get from a carb then perks back up.I can also smell fuel when the throttle has been mashed,also there are sometimes when I do this I can hear the engine ping like I'm lean on fuel,Once the car catches up to itself the ping goes away.it only lasts maybe a second or two.I did some searching and the only things I could come up with are either EGR, MAP or fuel pump.I know my EGR sucks but my car has had an EGR issue since I've owned it.I just replaced my fuel filter about 2 months ago and when I checked my fuel pressure yesterday it's at a steady 13.5 psi.I just replaced my IAC due to the last one failing.I haven't checked the MAP sensor yet but i'll have to get to that.Do you guys have any idea's as to what might be causing this? THanx in advance.

 

Check your feed line fuel pressure. If you do not see 9+ PSI you have a dying fuel pump.

Also, you may need to re-set the IAC. If you go to the bottom of the "new to TBI sticky" Dimented goes into detail on how to adjust and dial in a new IAC.

What is your base timing at (with the EST unplugged)?

To rule out the EGR you can plug the vacuum line from the EGR and see what happens. If the car runs the same it is not the EGR.

 

Feed line pressure is 13.5 psi. Base timing is set at dead nuts zero.I cleaned out the top end today with the car running with some distilled water.I revved to about 2000 and dribbled it through each throttle bore to see if maybe I might've had a hot carbon spot in the combustion chambers.it seemed to help with the pinging but the bog is still there.The car seems to be running pretty rich at idle.not enough to smell gas but just a rich exhaust smell.

 

ANYBODY ELSE?

 

Is this mashing WOT from a stop or from a roll?

 

Both,it doesn't happen all the time,some days it happens,some days it doesn't.

 

It might just be a simple matter of not enough fuel. When you mash the throttle, you're sucking all the fuel out of the manifold (hence the pinging). You have a lot done to your LO3, but it definately seems that some tuning is in order.

Hell, even with EBL tuning, my LO5 sucks the fuel out of the manifold from a roll. From a stop there isn't an issue, but there used to be before I had the old PROM dyno tuned.

 

Did it randomly just start doing this? Or has it been a persistant problem?

 

You might want to check the AE multiplier vs RPM table in RBobs code (I think he was using this). I think the AE is a pulsewidth in EBL. The actual AE a manifold needs is fairly constant across the RPM band, with a little more needed at low speed from my experience. The multiplier should be set up to keep the volume of fuel delivered during AE constant across the RPM range. It may not be getting enough at higher RPMs.

 

I have a 1985 camaro with a 305 bone stock and it will do the same thing I cant figure out the prob either.

 

It just started doing this about 2 weeks ago.

 

If it just started, then its likely something ignition or fuel delivery related. A faulty ignition will cause those symptoms if the spark is too weak to light the mixture during WOT or acceleration. It will also show up as a false lean on a wideband if you have one hooked up, and prduce a gassy exhaust smell.

 

An ignition spark should be blue or orange to be hottest? I think it should be blue but correct me if I am wrong.

 

I have an 88 TBI Camaro its does the same from a stop, from a roll Im ok it picks up great but at a stop it boggs out like a choking carb... Anything would help lol...-Rev

 

Should be blue/white with a nice snap to it.

 

Hmm, sound like a manifold being sucked dry.. With that 2'' Throttle bore, and 1.6 Ratio rockers, you may want to step the Fuel pressure up a notch, or get 350 Injectors.

Please Correct me if im wrong.

 

Yea, mine is an orange, so come tomorrow time for new Accel plug wires for the shorty headers and a hotter coil.

 

Fuel filter being clogged is a good starting point but I've ran into one lately that could not get straight. One of the problems was the dist module connectors had lost tension. A new pigtail from napa fixed the lack of testlight crossover at the PCM connector and took care of the default timing issues giving it the stumbles.

A dead spot on the TPS can cause stumbles aswell. Have seen temp sensitive dist modules cause bogging to.

I'd say check for crossover at the ECU since you have good fuel pressure.