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[euroboy]

well today i changed the maf with a ca18et maf. It has 4 wire maf and it looks the same as the ca18det maf.The car still stumbled. I revved a bit better but there is a problem.so i parked the car, installed the knock sensor on the pin 23 of the ecu connector. Still the same problem. I changed pcv still the same problem.Injectors are working properly. There is spark

just in case took out the spark plugs ro regap them to 0.040in and they were BLACK totally black, and they were brand new 2 days ago. Anyhows i regap them, put them in. Check the timing and the timing is fine.

Symptoms: I start the car, revs ok and then it stumbles. I rev it and it revs to a certain point and then it kinda misfires (burr burr burr) something like that.i let go of the throttle and it rev fine for like 2 secs and then it goes back to stumbling mode.Anyone knows coz it's pissing me off?plz and thanks!

[iliketocrash]

have you tried pully ecu codes? are your coil packs all bolted down properly? i know when i first started up my engine, i didn't have my coil packs bolted down because i didn't get any screws with the engine set. it was so much of a problem that at night i could see sparks arking from the coil packs to the head. after i bolted them down the car ran ten times better. also, is your power transistor bolted down and grounded?

[euroboy]

no i haven't tried pulling off the codes i will do that tomorrowthe coils are bolted down nice and they all got spark.transistor is nicely fit and grounded

now i would rev the engine up and it would rev hit a point and cut reving and sort of bounce a bit down and try again with no succes.

plugs are black with carbon. But there is spark alright....injectors are work and timing is correct.

any other ideas?

[euroboy]

ok warmed the car up, drove it for a bit then parked it with the car idling turned srew all the way clockwiseled flash 3 timesfully counter clock wise

i got ecu code 34 which is detonation.....

symptoms

car idles stumblycar hesitates to rev.car rev under full throttle but it hits a point where it refuses to rev, no boost

now i understand and the engine won't rev past a certain point because the car doesn't want to detonate....any ideas please?
Modified by euroboy at 4:34 PM 9/5/2004

[iliketocrash]

it isn't that your car doesn't want to detonate.. detonation is bad, very bad. The detonation sensor tries to prevent this. you probably don't have it wired up. i had the same problem. make sure the sensor is plugged in under neath your intake mani. then look for a plug from your lower engine harness that has one black and one white wire. it should be a gray plug. tell me if you find it.

[euroboy]

ok i know it was(can't find it on my s12 lower harness propably ripped somewhere) there but either way it wouldn't have done a difference....the wire goes from the lower harness into pin 23 of the ecu so what i did is grabbed the plug run a hard wire from the knock sensor to the pin 23 of the ecu....the wire from the ecu is green and white...so i tied them up and still the same thing.

I remember before my maf crapped out and i changed the plugs that the car was reving better(no power) but a lot better, now it cuts out.

ps:i know detonation is bad, but this thing is pissing me off

[euroboy]

can it be the transistor which has gone wrong?I pulled one plug out and it stopped, i pulled the other and it stopped...maybe it's not generating any V....

i am doing the test to it like the fsm says but it's not clear and i dunno wether i am doing it right or not.

i doubt the knock sensor will give me this much problems because the first day it wasn't connected and the car was reving fine...

[float_6969]

To be honest, this sounds like a MAFS problem. Are you sure that you have everything wired up right with the MAFS? You were talking about wiring up a different one. I don't think you can do that unless they are the same size. You might want to see if you can get a hold of a CA18DET MAFS and plug it in and see if it works. If you're really hurting for one, I could probabally sell you mine as I've got a Z32 MAFS that I'm going to use when I put the motor back in.

[euroboy]

actually i fixed that and i saw a major leak in the system. Once that was fixed too i took the car for a spin.It revved fine, it idled pretty good...so after warming it up with the ca18et maf WHICH ARE the samei boosted to 9 pound...

well i let go of the gas and now the car has a lot of trouble iddling. It's even worse than before, a lot of popping, it sounds like it's going to die at idle. I play with the throttle it misfires but eventually it picks up on the revs. I let go of the throttle the car dies and idles at 300rpm area. I can't see eny thing wrong with it as far as leaks go. Dunno if the fuel pump gave way, but there is spark on all 4 cylinders. The coils are good as well 2.8 OM of resistance. I can't see any leaks, and if it was a foulty MAF it wouldn't rev past 2k.

ps: ca18det and ca18et 87 have the same maf set up. Same size, 4 wire plug.

[float_6969]

See if you can't find some stuff called Seafoam. It's the most awesome stuff I've ever used. Dump a bottle of it in your gas tank the next time you fill up. I don't know that it will fix your problem, but it certainly won't hurt. I'm wondering if the fuel injectors aren't sticking or something. Have you checked the ECU codes since this happened? That is always the first place you should turn to.

[euroboy]

i did check my ecu and it threw code 34which i can understand since the car's knock sensor isn't hooked up.BUT nevertheless just the knock sensor won't give this much trouble. I know for a fact since when i fixed it and it was running fine the knock sensor wasn't there. Yeah the seafoam stuff is good but i have a problem here not just old stuff needing some tlc(but that's a good idea to get)i am thinking more along the lines of eletrical/leaksinjectors are pulsating fine and the resistance is there like the fsm says....

[r34 gtr]

i would def. check the fuel pump, if it was dead the car wouldnt run of course, but it may just be going out. its a good idea to change to a walbro or 300zx tt pump anyway. check the intake after the mafs, if its loose the car will run all kinds of badly. other than that i would try and get that code 34 buisness sorted out and see what happens.

- tim

[euroboy]

are you sure this time LOLj/k manfp is working good, but i will change to a carter set up.I mean 100gph is better than a walbro right LOLand half the price

[r34 gtr]

thats quite a beast.. why dont you just go get the bilge pump from a cruise ship and throw it in your gas tank. a few hundred thousand gallons per hour should work great!

- tim

[Bizz]

can you take a pic of the spark plugs? If it's fouling rich, then it might be a knock sensor thing with the ecu going full rich to prevent detonation. It might not have caused so much of a problem earlier because the plugs were not fouled.

Heres http://www.dansmc.com/Spark_Pl....html a spark plug list.....what did yours look like?

[euroboy]

it's number 3 but definatly not the timing!

[Bizz]

So if it's #3 we've got 1. A plug with a too high heat rating is being used and the plug firing end does not reach self cleaning temprature due to light load conditions

Unlikely. May as well check the numbers on the plugs though.

2. Use of a too righ a/f of richer than 8:1 ~10:1

Me thinks this is the case.....are you getting smoke out the tail pipe? Any fuel smell?

3. Trouble in the ignition system.

Uhhhh could they give a more vauge problem?

4. Improperly functioning cooling system resulting in excessive cooling.

Welp maybe, but thats not likely to cause your other probs.

My guess is rich, but that leaves the question why is it running rich? I'm guessing the ecu is freeking out with the whole knock sensor thing and going rich to try to fix it. I've got some pics of the harness (det) that has the knock attached. Come to think of it I could prolly snap some of the s12's knock as well if you needed it.

[euroboy]

when maf wasn't working i installed the new plugshence for 2 days the car was running rich due to the lack of maf.if the car cools excessively then the idle should be higher in order to reach the desired goal.Ignition system was working fine after i fixed those few bugs and the car was running great.I gotta check the fp.

[r34 gtr]

would def. check the o2 sensor and knock sensor. thats about all i could think of it possibly being.

- tim