Questions About Afm Problems

[yoshiii335]

Hello

I posted before I was having trouble with my car due to a fuel pump going bad.

Changed the fuel pump to a Nismo one, car drives better now, smoother. The car cut offs, the hard to reach 3000rpm problems went away.

But acouple of problems still happens. After hard acceleration sometimes, once or twice a day, the car will have no power(no cutting off), as if time froze. The car will be very slow but wont cut off, after about 5-10 seconds of keeping my foot on the acelerator, the car will drive normally again. Last night when I was doing some good driving, not driving too fast, just driving the car with good aceleration and going into boost sometimes, I came to a light, when it turned green and I acelerated and was shifting into third( was trying to pick up some quick speed aka go fast), the car drove very slowly, I kept pressing the acelerator and the car started jerking for about 3 seconds and than drove normally after that.

Things I have done in the past few months. Back in Nov last year, changed to new spark plugs, changed out old coil packs and wiring harness with known working used ones. I had a bad coil pack and the car wasn't running correctly. Before that there was some weird coil wire set up the previous owner had in the car. I returned it to stock. Car drove great after that.

When the hesitating, car cut off problem happened three weeks ago, I changed the fuel pump(it was dying), last week changed to a new fuel filter, and have cleaned the AFM twice within a weeks time. Two days ago when I last cleaned the maf, I bought a new pod filter (Aplexi) and installed it, the old one was dirty and worn. Also before I changed the fuel pump I took out the spark plugs and there was a little black carbon build up on the tops of the plugs, cleaned the plugs.

I have read and researched and it seems that it can be either my maf can be bad even after cleaning it, or bad coil packs, or bad ignitor. I am running a tuned computer and the spark plugs I changed out to are HKS with the correct gap and temp rating.

Changing to a new maf or new/aftermarket coil packs is expensive.

Any suggestions on what might be the problem?

[GTSBoy]

Cleaning the AFM will have no effect if the problem with the AFM is not that it's dirty. There are a bunch of other things that could go wrong, the most common of which is dry solder joints inside it. If you do some searching, you will find literally THOUSANDS of thread on here that start just like your post above.

There is only one sensible thing we can advise you. Put the car on a dyno, get a wideband stuffed up its arse, a fuel pressure gauge in the fuel line before the rail, a timing light, an ECU scanner on the Consult port and run the bloody thing until it gives you the problem and then you will at least have some measurements of the important variables likely to be involved. And don't complain that it costs money. We're sick of hearing it.

As to what it could be.....obviously the list includes;

AFM, dead dying or merely needing a resolder.

CAS, dirty sensor, wobbly bearing, poor connection to the loom, etc etc.

Knock sensor dying and causing shit in the ECU.

Fuel pressure reg possibly seizing open or closed instead of controlling properly ( a bit of a stretch, this one).

ECU coolant temp sensor being strange

etc

etc

etc

[GH05T]

definitely bad solder joints in your afm, cut it open and resolder them.

[yoshiii335]

  On 04/05/2016 at 12:04 AM, GH05T said:

definitely bad solder joints in your afm, cut it open and resolder them.

  On 04/05/2016 at 12:00 AM, GTSBoy said:

Cleaning the AFM will have no effect if the problem with the AFM is not that it's dirty. There are a bunch of other things that could go wrong, the most common of which is dry solder joints inside it. If you do some searching, you will find literally THOUSANDS of thread on here that start just like your post above.

There is only one sensible thing we can advise you. Put the car on a dyno, get a wideband stuffed up its arse, a fuel pressure gauge in the fuel line before the rail, a timing light, an ECU scanner on the Consult port and run the bloody thing until it gives you the problem and then you will at least have some measurements of the important variables likely to be involved. And don't complain that it costs money. We're sick of hearing it.

As to what it could be.....obviously the list includes;

AFM, dead dying or merely needing a resolder.

CAS, dirty sensor, wobbly bearing, poor connection to the loom, etc etc.

Knock sensor dying and causing shit in the ECU.

Fuel pressure reg possibly seizing open or closed instead of controlling properly ( a bit of a stretch, this one).

ECU coolant temp sensor being strange

etc

etc

etc

Stupid questions, well not stupid, but where is the knock sensor?

I am not having idling problems so would it be a CAS problem? from some of those thousands of webpages I have read, most say that when idling goes bad is when you look into the CAS, TPS, AAC Valve, etc.

  On 04/05/2016 at 12:04 AM, GH05T said:

definitely bad solder joints in your afm, cut it open and resolder them.

Ok, resolder sounds like something that would be easy to do.

Suggestions on what gauge solder to use?

[GTSBoy]

  On 04/05/2016 at 12:39 AM, yoshiii335 said:

Stupid questions, well not stupid, but where is the knock sensor?

I am not having idling problems so would it be a CAS problem? from some of those thousands of webpages I have read, most say that when idling goes bad is when you look into the CAS, TPS, AAC Valve, etc.

Ok, resolder sounds like something that would be easy to do.

Suggestions on what gauge solder to use?

The knock sensor(s) is/are on the side of the block near the oil filter. Do some searching on here for the large numbers of threads.

Bad CAS is more likely to turn up at high revs - especially if it is mechanically bad.

"what gauge solder to use?" The only question on the process that doesn't matter.

[GH05T]

yeah its literally open it up, heat up the joints with a tiny bit of extra solder and your done, mine looked fine, heated them up and just literally dabbed extra solder on it to make it liquefy and that's it. solved all my problems which were identical to your description.

[KiwiRS4T]

It is almost literally a waste of time changing out used parts for used parts. Is your Nismo pump a new one? Yes coil packs are expensive but when they get old they fail so a set of new ones should see you right for the next 20 years. Resoldering the MAF connections will cost you nothing so a good place to start. Did you gap your plugs down to 0.8mm?