Bogging, Sputtering, and a dash of Backfiring!

[blackout240]

K so blew my old KA engine and put new one in, wouldnt run for about 2 weeks. After going through every inch of this engine we finally found the problem and it was a bad distributer. So ive been driving it for about a week now and decided to race a civic, won by the way, and since that race it revs up to 5500-6000rpms and sounds like its hitting rev limiter, actually kinda sounds like im boostin. Now at 1500-2500rpm it chuggs and sputters with a hint of backfire. . . . . . . . . . does anyone know what this could be? Checked the MAFS but its fine.

[zstylelowrider]

Man my car sounds like it is doin the same thing. After a rebuild the car will start right up but when i try to give it gas it wants to sputter and chug. but if i slowly give it gas it wants to rev up fine. and once it gets fully warmed up the problem gets a lot worse.

[turboboost]

check for vacumm leaks, and check your o2 sensors, possible aaicv

[blackout240]

ya it seems to do it worst when its warmed up. like between 1500-2000 it will chugg and learch relly bad. theres no vaccuum leaks, cleaned the piss outta AICV, new TPS, new CTS, new gaskets (intake and head). this is just kinda weird that it was running fine and now it wont run.

[TK_Encore]

hey man thats the exact same thing im goin though right now. car had the problem when i first fired it up a few weeks ago. people will tell u its a vac leak or to check your plugs and wires, possible o2 sensor. those didnt work for me but u should definetly check those first. does yours make a loud kida clicking noise from the engine??

[blackout240]

Ya pritty much everything on my car is new from when i was tryin to figure out why it wouldnt start. But no im not really having that problem with the ticking. When I first start it up it runs great for about 10min then it starts doin it thang. Like when im @ 1500-2000rpm in 1st and 2nd gear it will start chugging down the road, and i mean my whole car. Then it taps out at about 6000rpm instead of 7000rpm making a gurgle sputter pop sound, kinda like a turbo'd car hittin redline.

[TK_Encore]

yea just like mine. it started kinda slow and would only do it around the 3rd and 4th grear mid rpms, but now its all over. every gear, all ranges of rpms, light on the gas or pedal to the metal. really sounds like its trying to backfire but its not. its compleatly bugin out now

[blackout240]

huh thats what mine is doin!!!! went to a nissan tech today and he said to run a ground from your ground on the MAFS to the block or a good ground. I tryed this and it didnt work but he said its most likely the MAFS being bad.

[zstylelowrider]

I can tell you a quick way to check your maf sensor. take a voltmeter and hit the farthest wire to the left and ground it to the battery. i am pretty sure it is a white wire. with the key on and the engine off you should see less than one volt. at idle you should see between 1.3 to 1.7 volts. and if you can get it to hit around 4000 rpms you should see anything between 1.7 to 4 volts. if this tests good shut the car off and switch the voltmeter to ohms and check continuity from the other two wires with the sensor unplugged to the ecu. if your ohm meter reads zero then the wires going from your ecu and maf sensor are good. i made the mistake of replacing mine before doing this test and ended up wasting my money.

[blackout240]

Well I just ended up replacing the MAFS and it didnt do anything. The ECU was also throughing a 33 code which is the O2 Sensor so we unplugged it and it ran like a champ for about 10min of driving and then went back to doin its thing!! Now it just boggs and chuggs throughout all RPM's.

[aziankingz]

im experiencing the same problem.. i think it can be the ECU?

[TK_Encore]

wasnt the ecu on mine i switched to another one and still the same problem, but it seems like i got really close the other day. there was a loose ground wire that deals with the injectors, i screwed that down tite and now it only does it every once in a while, so ive got to be really close...idk check there

[blackout240]

Ok so I put a 91 ECU in my car and it ran good for about 2 min then back to bogging. Then I got a new O2 sensor, put that in, ran good for about 2 min then went back to bogging. Got a new TPS, out that in, didnt do anything!! The funny thing about the TPS was when I unplugged it, it ran the same as when it was plugged in. I swapped out the 93 injectors with the 91 injectors but nothing positive happened, even though they are the exact same engine just though I might get lucky!

[dwclur]

Im also having the same problem and i keep seeing the same old check this check that but it all looks ood im mind boggled

[Varacity]

Read through the replys and did not notice anyone checking fuel pressure.

Check the fuel pressure KOEO and fuel pressure KOER. Also take the car for a ride and see if the fuel pressure drops or does anything strange.

Check for misfires. misfires may not be noticeable at idle, so power brake the engine around 2k rpms and see if you feel a MIS.

Sounds like the problem is fuel ralated or timing. Backfiring is mostly caused by running lean or bad timing. Also you say it seems like it is hitting a rev limiter, a clogged fuel filter will definately do this. Try bypassing the filter and see if you get a change.

Check your fuel trim by probing the signal wire of the o2s and ground. the voltage should fluctuate above and below 200 and 800 mV. If it stays mostly towards 200mV you are running lean and vise-versa.

Let me know what you find so I can be more helpful. Good luck.

[blackout240]

well I fixed the prob. after replacing the TPS and FPR it turned out to be two ground wires that go from the firewall to the side of the head. Wow all that headache and money and it was some stupid little ground wires that make the whole engine run. So if anyone is out there that is having this problem I would suggest checking all grounds first. Thanks for all help guys, im sure ill be back soon with more problems but in the mean time keep it sideways.