A couple weeks ago I started having the 4k hesitation issue that would cause my car to pop like its rev-limiting.

Since then I have redone all important grounds according to Aaron Cakes website. I have tested all the sensors according to the Fuel and Emissions portion of the FSM and they are all within spec. I rewired the fuel pump to a switch a couple months ago and with that I replaced the fuel filters lo and hi pressure. My actuators are not currently working properly because I have not wired in the RPM switches (S5 intake swapped on S4 block) but I have them wired open at this time. I know the injectors work and flow because I just had them cleaned.

I am out of ideas.

 

try a boost leak test

 

He's NA. Try again.

 

If your hearing a hissing then you have the problem I have. Today I gutted one of my cats cuz the insides were all over the place and put it back in and it helped but still not so good so im going to probably gut my other cat and hope its not too unbearably loud.

 

+1 to hissing cats

 

Sorry Racing Beat True Dual exhaust so it can't be an issue with the cats. Im thinking ECU at this point.

 

Oh sorry he didn't say was n/a

 

Check your secondary injector plugs.

 

Did you check the fuel pump? Take the filter off and look inside of the fuel pump. Also check your tank for debris.

 

"I rewired the fuel pump to a switch a couple months ago"

Is this just a fuel cut switch, or a switch to deliver power directly from the battery?

 

^If the latter, then that might be your problem as the power signal to the fuel pump is a step up/step down set up when using a stock ECU.

 

You regrounded the pressure sensor back to the engine block? With my old NA, that was not enough, I had to ground straight to the battery

 

Jerd my plugs are fine.

Texas turbo: no dice no blockage

Hozzman: it's the latter so might this be an issue? I've had it like that for almost a year now and it was fine.

Kungfuroy: I did reground the wire to the block. So you are saying you grounded it to the block and it didnt help so you reground to the battery and problem was solved?

 

yes worked for me

 

Yep, could be your issue. Try reconnecting the stock power wire to the pump and I'll bet you a quarter it goes away.

 

im having the same problem. hope you find the answer to this problem

 

Regrounded to the battery and still no good. Going to try Hozzmans theory right now will post results when done.

 

So when I reconnected the wire to the fuel pump I remembered why I rewired in the first place. For some reason the fuel pump doesn't get constant power like it should and would randomly lose power and cause me to stop wherever i was be it the freeway or a parking lot. The way I rewired it was to get direct 12V from the battery whenever the switch was activated. I have been meaning to add a relay but hadn't gotten around to it.

 

Wasn't the ECU bought a known good N326 and problem still occurs. I was intending on getting a 2.0 RTEK anyway and the convertibles N338 isn't recommended for the job.

Hozzmans solution is the best bet but unfortunately I do not know why in my particular case my fuel pump loses power intermittently while driving so I don't really feel like pushing my luck with it while testing.

I have also backprobed the secondary injector pins at the ECU (3H,3F) in my case and the main relay power (3I) to determine if the voltage saw a drop around 3800RPM as HAILERS2 suggested in another thread but instead found that they read 24 at idle instead of 12 like they should. I have no idea what this means and have a feeling Im doing something wrong. I have done the load test where you disconnect the pressure sensor and TPS and rev past 3800RPM and determined the secondaries don't fire. it isn't the injectors as I have tried several sets that are known to be good.

Also when resistance testing the injectors the 88FSM states that there should be a reading of 12-16Ohms but mine only read 3.2

 

So for anyone that cares it turns out it was my injectors. I had swapped to a pair of Cosmo 720s for a few weeks and during that time soaked my 460cc stocks in acetone to clean them. DO NOT DO THIS!!!!!!!! It ruins the coil windings and causes problems such as my own!!!! When I swapped back to the 720ccs (which I had been correcting as much as safely possible with my SAFC2) I no longer had the problem.

 

Primary or secondary injectors?

 

Well either one when you stick them in acetone for extended periods of time but in my case it was the secondaries.

 

Im gona try my injectors i have the same issue but at 6k

 

What year is your car?

 

is 90 gtu.

i had a msd box installed on the car. it was hooked up to the trailing coils. i took it off and the problem got worse. im going to change the coils first but definitely going to check out the injectors, fuel pump and filter