J240

Ok 90 zr1 I ve owned for 13 years only had a water pump and starter go. Get in it and drive as i go to step on it it bogs. like boggg. revs to 6500 but seems like when i press the gas down half way boggg. doesn't matter if the power key is on or off. i checked and replaced the secondary vacume pump no effect. will do this bogg even at idle as soon as i get to about half throttle . Is that the secondaries not opening . no difference at all with power key on or off. any thoughts as i'm at whits end. thanks

jrd1990zr1

Are the injectors original? Could be the cause. Check the engine warm resistance of the injectors. Could be bad primary injectors.

J240

Yes they are the orginal injectors but it only happends when i go to give it some gas at about half way injectors i would think would do it from the get go . is this what happends when the secondaries don't open it boggs ?

DDSLT5

Do you have a SES light on? If yes, what codes are present? If no - have you ever checked the MAP sensor hose for integrity? Just a place to start. Could also be that you have some oil in the MAP sensor itself. Check it out, it is dirt cheap, and it control fueling at part throttle. Good luck!

glass slipper

I'm guessing the TPS has a bad section in the carbon "ring". The TPS not only provides a signal for where the throttle position is to the ECM, but it also tells the rate of throttle position change. When the ECM sees a high rate of change in the throttle position, it commands a momentarily rich mixture to prevent a bog much like a carburetor accelerator pump does. If you can check the resistance of the TPS with an ohm meter as you slowly change throttle position, you should see a very smooth and gradual change in resistance. If you replace the TPS, remember you have to make an adjustment for closed throttle. I can't remember the exact adjustment but you have to set the voltage to something like .5V...I can get theexact procedure from the FSM for you if needed.

J240

The MAP sensor line is wet so I think Ill go that route. This just happend all of a sudden. So the MAP makes sense The SES light is not on and no codes set. I would think a code would set though if the MAP went or the TPS went . For that matter the SES light should set when anything goes cause it seems like it goes on whenever their isn't a problem! I will repost after the MAP is replaced thanks

J240

ok its not the MAP . just replaced it and no differnece has to be something with the secondary system as when it was cold it ran almost normal as soon as it got any temp started running like crap.

glass slipper

Ok, new symptom plus I went back and reread your first post so I have a few more questions.

1. When you barely press down on the gas pedal, does it bog?
2. When it bogs, does it ever recover and run correctly when you hold the throttle half open?
3. Does the bog not happen until you get to a certain throttle opening?

If the answer to #1 and 2 is "no" and "yes" to #3, it sounds like it may be fuel pressure related. It could be a bad fuel pressure regulator since it's suppose to increase fuel pressure as load increases and it uses vacuum to sense a load. As the car is warming up, the ECM commands a richer mixture with it tapering off the closer it gets to operating temperature and the extra fuel during warm up may be "covering" the bog. Just another theory...check your fuel pressure regulator for proper operation, it's cheap and easy.