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Discussion Starter #1
I'll describe the symptoms, and then tell you what I've checked already...

When first started and still cold, the car works fine. After 5-10 minutes and the temp gage comes up to between third to half way, the engine jerks and lurches above a certain rpm (don't have a tach), regardless of what gear you're in. When I finally get to 4th (4-speed) I can't get over 47mph. When sitting at a light, it will idle find for a few seconds, then suddenly start idling VERY slow and die. At stop lights I can keep it running by putting my foot on the gas lightly and holding it there.
While sitting in neutral, it will cycle up and down in rpms if I put my foot down a little more. If I put my foot down even more, it cycles up and down more slowly. When I let my foot off, it idles fine for a few seconds then knocks down to a really slow idle and dies right away. I can drive around okay as long as I prematurely shift and don't go over 47, but it looks to everyone like I'm learning how to shift.

I've spent a couple hours searching other posts, but haven't answered all my questions...

I took off the air filter housing to check things. All my vacuum hoses are only a few months old and I didn't see any that were cracked or loose. PCV valve is new. EGR valve moves and holds a vacuum. Air filter is clean. Gas filter is about 20k mi old. Plug wires and distributor cap are about 2 yrs old (bosch). Timing was checked last year. Plugs are a couple years old, should be fine, but I guess I could take one out.

The ECU gives a code of '12', which says air flow meter and associated wires.
To make sure, I cleared the ECU so that it said '55' and drove around again. Code 12 came back, so I'm sure it indicates a current problem. I took off the air flow meter and did the check suggested in the haynes manual (I think it's the same as the check in the FSM) where you apply battery voltage to wires C and E and measure the voltage at A and D for stagnant air and blowing air. It of course reads just fine (arg!), so I checked the connector contacts on both the female and male plugs, both looked bright and shiny and not bent or anything. I checked for battery voltage on the harness-side of the connection at terminals C and E and it is there. So according to the ECU, the AFM is bad, but according to the voltage tests, the AFM is good.

I thought I'd simply go to Napa and get an air flow meter and see if that did it, but turns out that nobody has the meter and the dealers want $187. CRAP!
Even the junkyards want $125-$135, of course they're crooks, what did I expect...

So, I guess what I'm wondering is...

Am I on the right track with the air flow meter?
There are 6 contacts on the AFM, but the manual only checks 4 of them. What are the other 2? Is there another check for the AFM that I can do?
Is there something else that can cause an error code 12?
Where to get an AFM more cheaply or somebody that has one I can borrow for the purposes of troubleshooting?
Will AFMs from newer sentras work?

Thanks for any help
 

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idle speed control valve, im bettin on it, its discussed a lot in here and its kinda like beatin a dead horse but your symptons sound like mine before i got rid or it cus i didnt wanan spend 100 bucks on a new one and there were none in the local junk yards. the iscv if u are looking at the engine standing in front of the grill is located on the left side of the throttle body near the fire wall, sticking out to the left its around 3 or 4 inches long and has a white plug on the end, when it starts acting up rev the throttle by hand and give the iscv a few good wacks , if it revs up when u do this then u know thats the issue
 

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i have the same problems but not quite as bad , when mine drops in idle it usually keeps itself from dieing. i replaced my idle speed control solenoid and it fixed it for awhile , but its goin to shit again. mine always shows code55
 

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Discussion Starter #4
okay, will try that

Okay, I'll test it as best I can according to Haynes and see what I come up with. Might be a couple days before this gets done... Thanks.
 

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Discussion Starter #5
Fixed it. Cost about $0.25. No new parts.

After checking both the air flow meter and ISC valve according to Haynes, both appeared good. Checked all wires back to ECC unit, all checked good. Sprayed off the wire elements of the air flow meter with carb cleaner (on a hunch from a friend) and reinstalled everything. Test drive: no problems!! Code 12 was gone and instead got code 55 (everything fine).

So, to anyone with the fishy symptoms that I had, first try spraying the MAF/air flow meter clean before you go disassembling and buying stuff, which we all know is freekin expensive.
Thanks for your help anyway. :cool:
 

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afm is on the same side of throttlre body as tps right? and its like kind mounted behind the tps? id like to try doin this to mine. my problem is similar except i have no problem gettin to 70 mph , but the car does surge and its annoying as hell
 

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Discussion Starter #8
no disassembly required

You don't need to take anything off except the cover on the air filter. You can spray the AFM elements off with carb spray by way of the air cleaner. If you look down the throttle body, after taking of the round air cleaner cover, you will see two passageways. The bigger opening has the injector (closer to the cab) and the smaller opening has a mesh screen over it (closer to the radiator). You can spray it off through that screen. It is a couple of wire elements and a small flat square element between two prongs. Be sure NOT to hit the wire element with the spray straw or it might break. My car wouldn't get past 47, but maybe a different story for you. Good luck!
 

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Discussion Starter #10
cleaning

I don't know if it matters. I did mine after I pulled it out, before realizing that I could have done it without removing it. I guess I'd do it while it's not running. Anybody else have opinions?
 

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horseshoe said:
I don't know if it matters. I did mine after I pulled it out, before realizing that I could have done it without removing it. I guess I'd do it while it's not running. Anybody else have opinions?
I don't know a lot about these cars yet, as I'm only researching at this point cuz I want to buy one, I just what to say that upfront. Now if that AFM is the hot wire type its my understanding that its really bad to clean them with the engine running and that it should be done with the car off and give it time to dry b4 restarting. Thats what I've always heard when cleaninng the AFM on other car's I've owned and repaired.
Slacky, you said you got rid of the idle speed control? Could you give some details on that and did it affect anything like fast cold idle? I just want to be prepared incase the sentra I eventually get is FI
 
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