Low RPM Load Hesitation/Slow Boost
#1
And the Revolution...
Thread Starter
Low RPM Load Hesitation/Slow Boost
I'm tired of searching. For the past 3 weeks I've been doing everything possible to get my car running right. I've done it almost all and now I need good advice. The hesitation comes on under light load below 3k rpms, maybe going up a slight hill. It does it worse when its colder and not completely warm. Even after it warms up it seems very sluggish all the way around. The car will crank up and idle fine. Was having a hard time cranking before and then I adjusted TPS and set idle. I've got the idle set right around 750 and when it gets completely warm its around 1k. I believe its running rich also. Cannot understand why. These are the things I have. 87T2, about 15k on RR Rebuild, street port, TB mod, walbro, koyo, blah blah. This car is my DD and I don't have a shitload of time to work on it because I'm working a lot, and it has to drive me to work because its my only car.
New Sard FPR - Vac off 39psi Idle 32psi
New 02 sensor
New plugs 7s, 9s
New Fuel Filter
New Borg Warner Thermosensor
Witchhunter cleaned injectors
Grounded ECU (4 wires)
Grounded Boost sensor
Grounded Coils all per Archives
And I made the RR Grounding Kit
No Emissions
Adjusted TPS 1k resting - 5.5 WOT
Has a rough idle but I would attribute that to the TB Mod and street port.
Its certainly running rich because after a hard pull I get A LOT of fire like 3 or more full seconds of flame encompassing the back of the car and after normal driving the bumper is darkening. I've been under the impression it could be a few other things, IAT sensor, AFM, or maybe even shitty TPS even tho its been adjusted and tested. I've probably forgotten to list some things I've got or done but if you ask I'll tell you. I haven't had time to run the Codes or test any of the damn voltages on the sensors or at the ECU because my multimeter is ****. I need help and after lots and lots of searching I can't seem to come up with anything. I know that I need to test all those but either I can't just yet. Hit me with anything
Chris
New Sard FPR - Vac off 39psi Idle 32psi
New 02 sensor
New plugs 7s, 9s
New Fuel Filter
New Borg Warner Thermosensor
Witchhunter cleaned injectors
Grounded ECU (4 wires)
Grounded Boost sensor
Grounded Coils all per Archives
And I made the RR Grounding Kit
No Emissions
Adjusted TPS 1k resting - 5.5 WOT
Has a rough idle but I would attribute that to the TB Mod and street port.
Its certainly running rich because after a hard pull I get A LOT of fire like 3 or more full seconds of flame encompassing the back of the car and after normal driving the bumper is darkening. I've been under the impression it could be a few other things, IAT sensor, AFM, or maybe even shitty TPS even tho its been adjusted and tested. I've probably forgotten to list some things I've got or done but if you ask I'll tell you. I haven't had time to run the Codes or test any of the damn voltages on the sensors or at the ECU because my multimeter is ****. I need help and after lots and lots of searching I can't seem to come up with anything. I know that I need to test all those but either I can't just yet. Hit me with anything
Chris
#3
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Join Date: Nov 2005
Location: South Bend, IN
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wow dude, you just described the same problem my car is having to a > T < . Lumpy, rough idle. Bogs and sluggish under light load. Let me know how it turns out if you get it fixed.
#4
And the Revolution...
Thread Starter
No I haven't done a compression test. I can't imagine why it would have a slow compression leakdown after only 15k miles. I don't hardly ever redline it or boost it to hell and back. I haven't bumped up the boost. I'm running premix also. The first tank I ran it without the MOP it ran fantastic. The second I mixed it too rich and it ran like **** so I drained the last quarter of a tank out and went back to the ounce a gallon mix. Could running it so rich that half a tank have screwed the injectors up?? Some of you ask how rich, I put in 16 ounces of premix to 13 gallons of gas.
#5
And the Revolution...
Thread Starter
I just took out the front leading and trailing plugs. The leading are a little black but the electrode is just lightly brown but the trailing are completely black like its not burning the fuel. And that would account for why I burned almost a quarter tank of gas last night only going 35 ish miles boosting once. It wasn't using gas this bad until I did that grounding job either.
#7
And the Revolution...
Thread Starter
Well I unhooked the ground that I had going to the Trailing coil and it seemed to get a shitload better gas mileage on the way to work, that was boosting 4 or 5 times. So no one knows where to get the AIT sensor??? Aaron? Hailers? Icemark?
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#10
And the Revolution...
Thread Starter
I know where its at. Where can I BUY one? And no it didn't fix the hesitation. I'm gonna throw some more money at it. Someone suggested ECU solder points??? Gonna do a search and figure that **** out. I'm gonna replace the upper/lower intake mani gasket and buy the IAT sensor. Then its back to the ole TPS and injectors. For some reason I have a feeling that the problem is going to lie in those. Anyone have any more advice or a similar problem that they had???
#11
And the Revolution...
Thread Starter
The car is unbelievably jerky when I let off the gas anywhere under 2500 rpms but I always thought that might be a byproduct of the street port, TB Mod and no emissions. Everyone else says its TPS.
#12
Sharp Claws
iTrader: (30)
5.5k ohms is too high for the TPS, try swapping it out with a different one. it should read about 4.1k-4.6k ohms at WOT, 1k at idle and sweep cleanly.
this could also indicate that there is a grounding issue still though, i see all your grounds but how about the battery to chassis/engine?
this could also indicate that there is a grounding issue still though, i see all your grounds but how about the battery to chassis/engine?
Last edited by RotaryEvolution; 06-25-06 at 04:18 PM.
#13
And the Revolution...
Thread Starter
I have all of my grounding wires, 3 4gauge wires going to a mounting spot on the firewall. Then they attatch to a single 4gauge wire that runs thru the firewall to my optima redtop in the passenger storage bin. The same with the power wire running from alt, starter connect to one thats not mounted to the firewall of course and runs thru the firewall to the battery.
#17
Sharp Claws
iTrader: (30)
41psi is what the FSM sais iirc, that is low if anything.
bucking is normally caused by leaning out so you may have too low of fuel pressure which will be more noticeable pre-secondary injector staging so that is one possibility but the TPS still sounds faulty to me, it could be a combination of the 2.
bucking is normally caused by leaning out so you may have too low of fuel pressure which will be more noticeable pre-secondary injector staging so that is one possibility but the TPS still sounds faulty to me, it could be a combination of the 2.
Last edited by RotaryEvolution; 06-25-06 at 04:58 PM.
#23
And the Revolution...
Thread Starter
But almost 5psi richer would make the car seem sluggish and if it was getting that much at a lower RPM then it would almost be choking it or wanting to bog it down correct? And the car runs richer when its cold anyway. I think this is why I don't see it hesitate a whole lot once its warmer. Because when it is cold the its almost running double rich.
#25
And the Revolution...
Thread Starter
Yea I know I'm running rich because of the plugs and brown bumper. Do you know where I can purchase the AIT sensor. I can steal it off my N/A Parts car correct? But I'd like to have a new one just to make sure.