skatingsamurai

FPR?...sorry im a noob i dont know what that means


i too am haveing a hesitation problem. unfortunatly mine seems MUCH worse. the power seems to cut out when i give hard gas in idle, but revs ok~ when i rev it real slowly.

and whenever i put any kind of medium load on the engine( letting the clutch out or accelterating) it bucks like a freeking bronco. One time i got so frusterated with it( because i tried grounding the ecu,boost sensor, leading coil, trailing coil, and fuel injection rail, changed spark wire spark plugs, changed the oil, tried fuel injector cleaner, AND octane booster) i just slammed on the gas and diddnt let go. diddnt really have any reasonce at first then ran,then hesitated then ran, then hesitated than ran then hesitated over and over again. And it was also doin somthing funky...like take the "d" in the spanish word padro, and elongate it....thats the sound my car was making when it was driving.

maybe its the coils not giving spark?
maybe the injectors are clogged?
maybe its electrical???
i need help either way

skatingsamurai

and my i not that i know i did just add this to the other thread i just wanted to see that i fix my problem as fast as possible. sorry if it has angered anyone

skatingsamurai

oh. another question. does the do the park coils give any extra spark when more throttle is given? or maybe the spark is spead up?

any replys would be greatly apritiated. thanks!

WAYNE88N/A

First of all, take off all of the extra grounds you put on, and clean up the OEM grounds...

Getting any codes?

Check your TPS second, do a search, or read it from the ECU using this...

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/troubleshooting-your-car-ecu-340578/

If it's not TPS, start reading your sensors while driving.

Could be fuel related (which you will see while reading out the O2 sensor), I'm having problems with my FPR as we speak, and at its peak of screwing up, she was bucking pretty bad...

Water thermo sensor loose connections can also cause this...

Adding grounds that "fight" each other will also, especially if one is near the alternator...

Got a lot of things to check- get busy

mwpayne

Listen to Wayne on that ECU check...I found my bad injector connection (causing the EXACT problems you describe) in 10 minutes using his method.
Thanks again Wayne!

WAYNE88N/A

Another satisfied customer, lol...

There are a lot of us that troubleshoot from the ECU, I'm not the first, I just happened to start the thread where we got all the info together for you guys for the different cars. Guys like Hailers and Hugues gave me the inspiration to start all that...

skatingsamurai

well at first i ran a diagnostics test on my s4 with there special lil wires that my friend let me borrow and the only signal that i was getting was a boost sensor signal....low and behold it was my FCD. I still grounded it anyways so that may not be the problem. ill double check thoughs grounds first.

thanks guys!!....or girls of course

skatingsamurai

you think it could be the coils?

WAYNE88N/A

Man, if you grounded that boost sensor, take it off. That fix was only for the early S4's, from what I've gathered. And lots of guys have made matters worse by grounding that sucker...

Boost sensor codes are a dime-a-dozen on our cars. I get 10 to 15 of 'em just driving to work, lol...

I don't think it's the coils, I think it's electrical, ground related...

skatingsamurai

ok well then do you think i should try grounding something with the injection harness/ fuel rail/ somethin i may not know about?

WAYNE88N/A

No, I think you should remove all of the grounds that aren't OEM, and check the OEM rear rotor housing ground from the ECU (pin #'s are in the writeup). If you get less than 1 ohm from the ECU pin to a bare metal point near the ECU, they're good. And, if you happen to have the UIM off, visually check and/or clean up that ground. Also clean up/check the tranny-to-firewall ground...

Not flaming, but you guys just don't understand what you're doing to the ECU when adding all these grounds...Especially the extra engine to chassis ones you're putting on...

Have you checked the simple things first, like TPS, fuel filters, etc?

skatingsamurai

i replaced the fuel filter and im checking the tps today

skatingsamurai

it kinda has a lumpy idle.....like there is a momentary pop, kinda like its missing,could that have anything to do with it?. oh also awile back i accidnetly broke the line that returns fuel to the fuel tank.( located rear right wheel well. bout a foot in on the underside of the car. could that have anything to do with it?

Nova7

iTrader: (5)

Wayne already mentioned it, but check the Water Thermo Sensor right at the bottom of the Alternator, a green connector I think. I knocked it loose doing something to the alt. once on my GXL and it was causing all kinds of hesitation and bucking throughout the rpm range.

HAILERS

Try this: disconnect your TPS and go for a ride. Did it act different?

Or this: Pull off the vac line to your pressure sensor and plug the vac line with a bolt. Go for a ride. Did it act different?

skatingsamurai

oook i checked the tps(diddnt take it off)hte NARROW was reading aprrox .551 ohms. it wouldnt let me take a reading for the WIDE? ummm i did (attempted to do an ECU check but i dont know how to do back probing so i havent been able to take any readings when i have been driving. so i checked the questionable ones that i thought might come not rgith with the key in the ON position. and i checked the following
1T crank angle sencer- it read 5 volts...thats 4 higher than its suppost to?
1V (cant remmember what this was - 1.2 volts/ couldnt get a reading while driving.
1x trailing coil 4.3v
2B pressure sensor 12.2 ...was suppost to be 2.3-2.7 (i think someting is wrong here)
2D o2 sensor .9v
2I -1.2v
2N egr solenoid valve 12.27v was suppost to be 12
2P 12.27v
2Q 3.0v wtf?
2R ground -0v
3A ground -.1v
3B ground -.1v
3C injector -12.27
3D feul pump resistor relay- 12.33v
3E injector -12.27v
3F injector - 11.9
3G ground - 0v
3H injector 12.32v
3I main relay- 12.30v
3J battery - 12.28

skatingsamurai

i want to take readings on the injectors and the grounds as the car is running but im not sure how to.
also i checked the water thermo on ecu ...reading was ok and no visual damage.

OH! i almost forgot the coils. i took the ohms on thoughs and they were below 1 when car is off, and i also took the ohms for the crank angle sensor they were nominal (110- 212 i think?, it read 162) i want to take the voltages of the coils as my problem presents it self when running.

i am also in the procces of checking the air flow meter....i was getting 2.5 ohms for all the lil prong thingys on it EXCEPT 2 on one side.. so if you guys could tell me if that is normal or not that would be awsome
thanks!!

skatingsamurai

OH ONE MORE THING. uhh if all else fails im taking my car to a mazda dealership to have the feul pressure read. and somethin else but i forget what.

just thought i would mention that

WAYNE88N/A

Hmm, first off read this, if you haven't already, and I'll go scare up my book to compare to your numbers

https://www.rx7club.com/showthread.php?t=340578

skatingsamurai

i dont have alligator clips...i am somewhat afriad of frying my ECU

WAYNE88N/A

Lol, you're not going to fry it, all of the voltage checks are passive tests- you're not "inputing" anything into the ECU, you're just reading voltage potential to ground on a pin/wire...

Get a small piece of stiff wire to shove in the plug on the pin you want to read(a small paper clip might work), and then use something to hold the positive meter lead to the wire for good electrical contact. Just make sure the wire or the meter lead doesn't touch ground...Then you just shove the black meter lead anywhere that's a ground, and that it'll stay in while driving. Jumper wires with clips make life a whole lot easier, but they're not a necessity...

You don't have to remove any of the plugs for the voltage checks...

You can do so much more while driving, than just doing the "static" checks at idle, because the sensors will show their full voltage ranges while driving...Especially TPS, AFM, O2 sensor, injectors, water thermo...

WAYNE88N/A

OK, first a disclaimer, I don't know exactly which pins are different between the turbos & NAs, maybe Hailers will chime in if I get some of these wrong...He loves it when I'm wrong, lol...

1T- how the heck are you getting 5v there? Maybe you have super magnets in the CAS, lol...

1V- the leading coil ignition timing signal, doesn't sound too far out of whack, but is kind of high...

1X- the trailing coil signal, this one is way high, weird...

2B- there's no way in hell you should be getting 12v back from a 5v input, lol...Have you played with the wiring at the boost sensor? Got any "new" ground wires in that area? Get 'em off of there...Now...

How's your reference voltage (pin 2A)? Should be about 5v...

The only way to read 3v on 2Q is if the ECU is having the BAC work extra hard to maintain an idle (we're talking a 75% duty cycle here), which means you have idle issues...

Your rear rotor housing gang ground might need to be cleaned up a bit, but .1v is not catastrophic...

Is 3B a ground on the turbos???

Injectors look OK...Was this at idle, or just key on?

skatingsamurai

well before you say anything..... how do i make sure i have the TPS i just put in tuned right ..... i think i have already fixed the prob

WAYNE88N/A

I adjust my TPS exclusively from the ECU pin, and since you already know how to get at it, you might as well too ...Remember your idle needs to be around 750...After you adjust it to 1 volt, turn the car off, turn the key back on, and push the peddle down SLOWLY, you'll see the TPS's entire range, which maxes out at about 1/3 throttle, BTW....

skatingsamurai

its was all at key on....and at least i thought it was a ground lol...i thought it was ground ground then to the injectors 3c then feul pump?3d? ill have to check there any reason (possibly ground reasons that there reading high?

But at any rate.... i changed the TPS and i took it for a drive, no bucking!!!! now i just have to adjust it and i dont know how

might check my crappy *** haynes manuel