car bogging down when flooring throttle

[TJ Schulze]

this is on a 1990 Dodge Daytona with the factory electronics and a boost button programmable chip. I am running a 2.4 srt4 motor.

when I put the car to the floor weather on the road or in neutral the car goes up to about 3200 rpm and then falls flat like its running out of fuel and drops down to about 1200 rpm then comes back up again just bouncing back and forth between 1200 and 3200. if I go into the throttle easy it will go clear up the red line with no problem.

fuel pressure is good right at the 53 psi, goes to 60 and holds there even when the motor bogs down.

so far I have replaced the fuel filter check the map sensor and swapped it out with the new one check the throttle positioning sensor and all my grounds. when I do hammer on it like that even If have it in neutral, when I let it idle again the idle is very rough just barely idling, if I then turn the car off and start right back up again it idles fine. my afr is sitting right around11 even when it Boggs down.

this is really got me stumped so any help I can get on this works surely be appreciated.

[acannell]

first thing, since its so easy to do, and would be an absolute easy fix, while the car is idling, wiggle the HEP/ignition sensor wiring coming off the distributor

second, wiggle EVERY electrical connection and wire you can see..if you can get the problem to occur that way, you are done in 5 mins....cheap, easy, fast

if none of that works, then:

-when did this start happening? what change to the car is it associated with?

-what cal do you have in the boost button chip?

[TJ Schulze]

okay first off I'm running a modified srt4 Cal but I don't even remember where I picked it up from. this happened right after I had to pull the transmission out and to replace the clutch. I broke my tps while doing the transmission and had to replace that. I did check all my wiring and connections cuz I figured that was the first problem I had, but could not get it to repeat itself by wiggling wire connectors. while I am pretty sure it is a wiring issue I cannot think of what part of the system would cause it to do what it's doing.

[acannell]

okay first off I'm running a modified srt4 Cal but I don't even remember where I picked it up from. this happened right after I had to pull the transmission out and to replace the clutch. I broke my tps while doing the transmission and had to replace that. I did check all my wiring and connections cuz I figured that was the first problem I had, but could not get it to repeat itself by wiggling wire connectors. while I am pretty sure it is a wiring issue I cannot think of what part of the system would cause it to do what it's doing.

is it possible your cal is not running very well?

[TJ Schulze]

well it has been working really great but I suppose it wouldn't hurt to dump it and reload it and see if that makes a difference. it only takes a couple minutes anyways so I will do that now and take it for a drive and see what how it goes

[TJ Schulze]

I reloaded the calibration and the car still operates the same no change no difference. next I think I am going to pull the 60 Way connector and check resistance to all my sensors. I have had issues in the past with connections between the 60 Way connector and the ECU.

[acannell]

I reloaded the calibration and the car still operates the same no change no difference. next I think I am going to pull the 60 Way connector and check resistance to all my sensors. I have had issues in the past with connections between the 60 Way connector and the ECU.

do you have a way to datalog? if you are using a boostbutton setup I would imagine you have mpscan and the sci cable right? you could log a bunch of sensors at once and see what happens during the bog

[Daytuna]

Sounds like the timing is off by one tooth.... I've heard that if you're off by a tooth, you're motor will run and work, but wont be able to run correctly at WOT.

Just a thought...

[TJ Schulze]

Update: I was checking my sensors using mpscan and the only thing I saw strange was the output from the o2 sensor. It was going off the scale lean when it boged down. This contradicted the reading from my wideband which said l was going rich. I hooked up a narrow band o2 gage up and it showed the same as mpscan, going lean, as in off the scale. This was with 60 psi fuel pressure while bogging down. Today I will swap out the o2 sensor and see what happens.

[TJ Schulze]

I finally got this figured out a while back and am just getting back here to update. The problem was the TPS. The new one I bought was the wrong one. I was given one for the non-turbo setup.I found it strange that all the tests said it was good, yet it didn't work right. Now for the bad news, you can no longer get a TPS for a 1990 and older turbo 2.5. Discontinued item everywhere i checked. I ended up switching to a 1991 throttle body that i had from a turbo motor laying around. I had to change the wiring connector, but it did the trick.