Just an update about the MAF on my '99 F-150 4.2L, 120K miles I reported about in December. Remember I had posted a thread about my MAF going out and that Ford told my mechanic that the AirRaid system was the culprit. I spoke directly with AirRaid and they assured me that the system was not the culprit but that I might possibly but very unlikely though could get some excess oil from the filter on the MAF causing it to act up and that it could be cleaned. However, I ended up needing a Throttle Position sensor and a couple of vacuum hoses in addition to my MAF. Truck ran great about 28 days. Last week when I started it one cold morning, it turned over and died. I cranked it again and it sounded like it was sucking in tons of air like a vacuum leak or something. Idles rough. I need to keep giving it gas to keep the rpms up during stops. about 10 to 20 miles later "vacuum leak" sound and bad idle stops and it runs great. I took it back to my mechanic and he immediately targeted my MAF again saying that it was the AirRaid system. They replaced the MAF again for free. I told them that I wasn't buying the whole intake system being the problem. The next morning it did the same thing again. I spoke to a different shop - Ford Performance Specialists (FPS). I explained to him what was happening. He didn't believe it was m intake system either. He said it was probably my IAC and/or another vacuum hose leak. I cleaned my IAC - no luck. I replaced my IAC. It still died on first start. So I put my original IAC back on. Does anyone have any suggestions. I would like to fix it myself before I take it to FPS.

ANy insight to this crazinees would be much appreciated.

Ralph

 

Have you checked very carefully for vacuum leaks? Possibly a sticking EGR valve?

 

No I have not checked for any additional leaks since the first two were fixed. Is there an easy way to check the EGR valve?

 

With the engine idling the pipe from the exhaust manifold to the EGR valve should be cool as there should be no exhaust flowing through. If the EGR is sticking the pipe will be hot like the exhaust manifold.
You can also loosen the bolts that hold the valve to the intake and slide a piece of tin in between to block off the ports. If that makes a difference then you know it was sticking open.