# 92 Stanza, engine rpm revs and falls



## rt76 (Aug 24, 2005)

Hi, I'm new here and I've read all the stanza forums looking for my problem but I don't see it.
After my engine warms up on my 92 stanza, the rpm starts rising and falling continuously. If I give it more gas, the rising and falling increases in intenisity.
Here's the background and the car has 160,000 miles on it but has run great and uses no oil. The engine was starting to idle a little rough, so I took off the air hose from the filter to the throttle body. With the engine running and me revving the engine, I sprayed throttle body cleaner in to the throttle body. When I got through and replaced the air hose, the engine was idling fine so I shut it off, thinking I had fixed my problem. Next day, after driving about 15 miles, the engine started fumbling and missing so I stopped. Then the engine started revving up and down like I stated previously. I was able to drive it home. Upon inspection, I noticed that the air hose I took off had torn, so I replaced it with a new one and made sure all the hoses that connected to were on correctly and that those hoses were in good shape. I did notice that I had knocked a vacum hose off the egr valve that came from the vacum canister. I replaced that hose. The engine still races up and down, after it warms up. Until it warms up, it runs great. Also, when I rev the engine and let off the gas, the engine idles fine for about 4 seconds and then starts racing up and down again. The racing up and down is continuous and the up and down intensity is about every second or 1-1/2 seconds.
Did I mess up some kind of sensor or block something when I sprayed the throttle body cleaner? If I disconnect the mass air flow, the engine will quit so I assume it's ok. Could it be the idle air control valve or did I block the port for that. I can't find that port, does anyone know where the ports for the idle air control valve are?
Any help would be appreciated. Thanks


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## de2r (Aug 6, 2005)

Have you checked the level of your coolant? You could have air pockets that are effecting the Idle Air Control valve.


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## rt76 (Aug 24, 2005)

de2r said:


> Have you checked the level of your coolant? You could have air pockets that are effecting the Idle Air Control valve.


The coolant level is ok. I don't understand how that would effect the Idle air control valve, could you explain.


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## rt76 (Aug 24, 2005)

Found the problem. I got the codes off the computer and it gave me a 12. that took me back to the mass airflow sensor which I had thought was ok. I pulled the MAS to look at the filaments to see if they were broke. I had to put my bifocals on to look at the filaments and when I did, I noticed a crack and hole in the top of the plactic cover that covers the electronics on the MAS. I sealed that crack and hole and the car runs fine.


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## rt76 (Aug 24, 2005)

rt76 said:


> Found the problem. I got the codes off the computer and it gave me a 12. that took me back to the mass airflow sensor which I had thought was ok. I pulled the MAS to look at the filaments to see if they were broke. I had to put my bifocals on to look at the filaments and when I did, I noticed a crack and hole in the top of the plactic cover that covers the electronics on the MAS. I sealed that crack and hole and the car runs fine.


It didn't run fine for long. I bought a new MAS and it didn't help either.


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