Bogs for a second and then takes off

[Paul Workman]

Well, kinda piling on, but mine too sometimes cuts out on hard decel when getting back on the throttle. I'd like to hear what Marc says about it, as I too have the same issue with the secondary delete - have had for 6 years now. It can be aggravating, but only happens on hard decel after running for "a while" in spirited driving conditions.

It isn't a big deal as it doesn't crop up all the time. But, I'd like to get to the bottom of it one day.

[Dynomite]

I have a 91' with secondaries eliminated and RC Injectors.

Three 90's all with RC injectors and secondaries including starter reconditioned like new.

All four ZR-1s have Haibeck chips.
All four have TB coolant blocked at Injector Housings.
All four have the Starter Relay installed.
All four have Jerry's gaskets and SS bolts.
All four have full compliment of Carter Bling

All four accelerate like greased lightning with NO bogging or hesitation in any gear at all RPMs

Oh.........And a 90' (L98) with Haibeck Chip......also greased lightning

[WVZR-1]

Originally Posted by Dynomite

All four accelerate like grease lightening with NO bogging or hesitation in any gear at all RPMs

Oh.........And a 90' (L98) with Haibeck Chip......also grease lightening

Just what is "grease lightening"?

I've seen "GREASED LIGHTNING" used in reference to maybe fast or speedy BUT "LIGHTENING" confuses me.

[Dynomite]

Originally Posted by WVZR-1

Just what is "grease lightening"?

I've seen "GREASED LIGHTNING" used in reference to maybe fast or speedy BUT "LIGHTENING" confuses me.

I am a poor speller

Just got done making a set of New Oil Cooler SS Braided Hoses with Aeroquip re-usable fittings for a 90' ZR-1 and they fit perfectly first try.
I cannot spell "Aeroquip re-usable" sometimes but the hoses are perfect

I will take a photo tomorrow after I degrease (here I go again ) the little bit of oil spilled while doing the change over to SS Braided hoses.

I will try some runs tomorrow also to see if I can get it to bog or hesitate at all.

[WVZR-1]

Originally Posted by Dynomite

I am a poor speller

LOL - me too I believe

[Bearly Flying]

I have the same problem as the OP, ported plenum and IH's, secondary delete.

The car runs very well except for when it is in low throttle positions. ie normal traffic stop and go conditions.

Any periods of light or no throttle positions seem to generate a rich condition and flood the motor.
A decisive hit on the throttle will clear it's throat and all is good until the next lite throttle event.

It's not all that fun when you are in stop and go traffic.

I believe we are flooding the motor at low throttle positions.

[BennieC.]

It appears that Z owners that is having the problem have in commons are: 1) the secondaries eliminated
2) Haibeck chip

How about the injectors. What injectors do you have currently installed. I have talked to Marc in regards to this concern and he has 2 1990 that are doing the same thing as well. He suspecting injectors. I'm going to data log and check the car out this weekend. Will let you know what I find out. We can make some changes to the fuel trim if need be.

[Bearly Flying]

I have FIC injectors from Jerry.

Headers and a 3" exhaust, Ported plenum and IH;s, port matched heads. If that helps....

[Marc Haibeck]

Hi Bennie,

I resolved the problem that I was having with the car that was bogging or stumbling under light loads.

This is what I was seeing in the scan data. When the engine would bog the short term fuel trim would go down to about 90. As if the the fueling was really rich. Then the oxygen sensor voltage would then go to less than 50 mv. This would close the fuel injector and I would see 17 to 20:1 AFR on my wideband oxygen sensor.

If the calibration was set to open loop the car would drive perfectly so the fuel table was correct. I eliminated the problem by replacing the oxygen sensors. New sensors respond quickly to fueling anomalies and don't get stuck down at less than 50 mv when responding to a rich AFR.

[XfireZ51]

Marc,

You may recall I was chasing an issue w my O2 sensors earlier this year. Particularly the pass. side. On a scan, I would see a string of 0's for the voltage, which thee ECM would interpret as running lean. If that condition remained long enough, it would throw the LEARN function OFF and default back into Open Loop.
W a bit of accelerator, things would come back. You wouldn't feel any difference as it did that, but for purposes of tuning it would throw things off.
Some other tuners I communicated with suggested that AC O2 sensors were more consistent than the Bosch so I got two of them off Amazon. Voila!
No zeros, no open/closed loop flipping, no going into and out of learn.
However, I can't say that I experienced the bog others are sensing. I do see that on closed throttle decel, my WB will sometimes spike to 17 or 18:1 AFR.
I wonder if that's not the injector shutting down due to a too small pulse width being commanded, which brings up the issue of the injector offset. Another tuner using the ACCELs in a different motor saw the same thing happening