HAILERS

That fuel pump pressure sucks. Seeing as how you installed a new pump, I'd try another pressure gauge.

IF the engine was not running when you did the *T*, the pressure should be around 37-39 psi. If the engine was idling, the pressure should have been 28psi but frankly I see around 31-32psi on the cars I've looked at (at idle of 750 rpm).

I foget and am not going to look in the FSM, but the pressure coming out of the pump and just to the gauge, or deadended so to speak, should have been in the 70-80 psi range. See the FSM for the right figure.

I'd bet it's the gauge myself.

The lack of the ACV and anti afterburn can cause backfire as mentioned above. Another thing would be a TPS problem. When you let off the throttle the TPS cuts fuel to the injectors. That act should cut down on backfiring all by itself.

Nick86

iTrader: (1)

**Ok, update with Video**

The fuel pressure I listed here was before I replaced the pump. After I replaced it the problem didn't go away, but it did change a bit and become somewhat intermittant. After replacing the pump, I timed the car with the green check connector jumped and did another test for vac leaks and loose connectors. Then I went for a drive:

Video:
http://smg.photobucket.com/player.sw...0288&os=1&ap=1

Sorry for the questionable quality of the video, but it does show you what's going on! In the video you will see:

1. The car idles perfectly at 750.
2. I accelerate lightly to 4K without issue.
3. I then accelerate to 5K. The car then stumbles and misses right at 5K, so I shift gears and keep accelerating. This time I run it to 6K without any missing or hesitation. I shift gear again.
4. This time at 4.5K the car misses and stumbles badly. That's not me lifting off teh throttle, it's the car. After a few secons Ileft off the gas and slow down.
5. From idle I accelerate lightly and at 4K it starts to miss and stumble. I shift and keep accelerating. This time it goes from 3K all the way up to 5.7K without any problem.

Disregard the oil pressure gage, it's unhooked in favour of an aftermarket unit.

So that's where I am now. Thoughts?

Thanks,
Nick

Nick86

iTrader: (1)

Also, since replacing the fuel pump, it's a lot harder to start when hot....

freemanrx7

Are the orignal cats still on the car? Your profile doesn't mention anything about that.

Nick86

iTrader: (1)

No emissions equipment at all.

Nick86

iTrader: (1)

Ok, another update:

I hooked up a timing light to the L1 lead, and held the lightinside the car while driving. When the car stubles and backfires the light never stops blinking and never seems to break its rythm. I did the same thing on the T1, L2, and T2 wires and got all the same result. To me this means taht the spark is Ok.

Now, for the bigger issue!

I put a pressure gage right at the FPR (on the end of the secondary rail). With the ignition "ON" and the yellow check connector jumped, there was ZERO pressure. I went for a drive and the gage read zero the whole time! I released all the pressure in the fuel system and remmoved the FPR - and the fuel rail was still preasurized... it sprayed fuel all over... super. Anyway, the FPR seems to be siezed closed, and no amount of vacuum pressure will open it! If this isn't my problem, it certainly needs fixing!

I'll try replace it and see what happens....

Nick86

iTrader: (1)

New FPR - No change.

On the stock FPR, how hard is it to move the plunger inside? Should it move with light vacuum pressure? What about pushing it with a screw driver?

pfsantos

iTrader: (1)

I re-read every post and don't think you've told us what the spark plugs look like. Pull them out. Also, are you sure the secondaries are firing (a previous poster mentioned how to do this). Another thing - since you took the ACV out, did you plug the pipe at the back of the intake manifold? What about the solenoids for emmissions - you don't want them causing vacuum leaks - make sure all lines that went to the ACV are plugged. Get someone to stand by in a parking lot as you pass them while the car is hesitating (someone with a good nose) and see if it smells rich or black smoke. How does the oil in the engine smell, a lot like fuel - is it diluted?

We're not giving up on you yet!

scrip7

iTrader: (6)

After watching and listening to the video, it sounds like more of an intermittent ignition misfire rather than fuel mixture. Fuel mixture problems are more predictable, I noticed sometimes you can accelerate right through the point where it first stumbled. Check spark plugs first. Hopefully you're using NGK plugs. Also check plug wire routing.....make sure you don't have them "bundled" together with a twist tie or cable tie. This is common for people to do and the result quite often is crossfiring between 2 or more wires, especially on humid days. Use plastic plug wire separators from a parts store. Try to keep the plug wires 1/32 inch or more apart. If there is arcing, you can often see it by looking where the plug wires come closest together, if you see a dusty white residue where they meet, arcing has occurred. Another way to check for that is to spray a fine mist of water on the plug wires and watch for arcing as you blip the throttle by hand. Or, watch for arcing at night, darker the better. Any of the coils can also be weak, but that shows up best on a scope.

archangelkn

I recently had a problem almost exactly like this... My car was sluggish and wouldn't even make it up easy hills with WOT... I replaced the spark plugs and ignition wires on a whim, and it fixed the problem.

I noticed you changed your spark plugs already... Did you make sure you put the leading plugs in the upper holes and trailing plugs in the lower? There's a difference between them but I don't know if it would make a big difference.

archangelkn

http://www.aaroncake.net/RX-7/grounding.htm

Did you just reground the engine at the starter and the shock tower or did you also remember to get the ecu too?

DaBrkddy

From the video, it sounds to me like ignition. It wouldn't matter if the timing light you hooked up flashed, that's all great, but if your wires are bad or hooked up wrong, the timing light won't tell you that. Replace the plugs and wires, see if that fixes it. (If it doesn't, it'll at least run a little better.

RotaMan99

Your TPS should not be causing that problem. Just to eliminate that though, you can easily unplug it. Take it for a drive and see how it runs. I don't think its that though.

Its sounds like the Secondary Injectors or atleast a fuel problem.

Vacuum leaks wouldn't cause this.


You would see zero fuel pressure at the FPR since thats the return line. You want to check the pressure on the fuel filter line (pressure side). Check it with a different gauge while idling and then disconnect the FPR from its vacuum source and check the fuel pressure again to see how much it raised. Just trying to eliminate a bad/stuck FPR.

Im not following you here. How did you go about releasing the fuel pressure? If you released all the pressure in the fuel system, there wouldn't be rails wouldn't be pressurized, and removing the FPR would release all pressure and fuel.

My car did this to me once but I can't remember why. I think I induced it while screwing around with stuff so it was easily reversible but I just don't remember what I did to make it happen.

TehMonkay

iTrader: (-1)

Thats the same thing mine is doing when cold, except not as bad.

coldfire

iTrader: (1)

Nick sorry to hear you are having problems with your car. i hope you get this figured out soon. this is my take on it:

it seem that you have an ignition system issue.
check your spark plugs and if it looks like you are running very rich then this is a good hypothesis.
checking if sensors or electrical components are "in spec" sometimes doesn't actually tell you if they are operating properly. for example an ignition coil may fail or work intermittently and it's hard to test for that.
i think the ignition coils might be the problem, have you tried that yet?

RotaMan99

I looked at the video again and it does seem like ignition. Hard to tell cause fuel pressure problems will do the same.

Toxindude

I watched you video I noticed you can get right past where is would normaly . Hes . Can changing the plugs or wires really get rid of hes ? My car somtimes you can get past 3800 in first gear then somtimes not and it never gets past 3800 in anyother gear unless im barley pressing the pedal down but that dont get me anywhere . And it the car runs and revs right past like sob ports kickin in and everything .

Digi7ech

iTrader: (1)

You've replaced a lot of things but did you check the harness?

I had a crazy bucking in my car and it turned out that the harness rubbed against some metal and slowly cut throutgh the wires and by chance it woudl randomly ground out my secondary injectors. Boy was that fun.

Test the secondary injectors while driving.
A mechanical Volt meter is best because you can see the bounces but a digital one will do(it reads slower). Just stick it in the Pins at the ECU for the injectors and drive at the 3800 point. Watch them turn on and see if they are doing their job and in rhythm

TalkSick

this will probably sound pretty odd but my throttle cable was causin a similar issue. if it only happens at certain rpms then disregard but i found my throttle cable was loose an when i let off the pedal, even slightly, it would buck, usually causin my foot to tap the pedal again causing it to start bouncing until i let off altogether. just figured id throw that out there since it looks like u tried everything else