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New to this site, I am RW1998. I am trying to help an older vet with his 1999 B3000 with a 3.0. The truck idles at 850rpms. When it starts it idles at around 1000 and runs very rough. When I disconnect the IAC the engine dies. The AC also has problems it blows cold at idle but at highway speeds after 7-8 minutes running the compressor kicks out. One can turn it off and it blows cold againg after a few minutes. Any ideas?
OK, these IAC's are starting to be a maintenance item that everyone should look at when doing oil changes. Remove IAC and clean with some throttle body cleaner, NOT carb cleaner!! Is there a CEL?? If so ,what codes?? Can be checked at all big box auto parts stores for free. When was the last time the fuel filter was replaced? I'm sure this vehicle has a MAF (mass airflow) sensor somewhere in the air intake system. It should be cleaned with MAF sensor cleaner ONLY-do not use throttle body, or carb, or brake cleaner-these will leave a film on the tiny element that you DO NOT WANT to touch with anything!!! Spray it-it will air dry in 30 seconds. Dirty air filter is not good. Plugs, and wires, not been replaced in a long while, possibly needs to be addressed. Clean the throttle body inside and out, as it will help driveabilty, and mileage, as will the rest of the items I've mentioned. If you can check fuel pressure do so (you can rent from big box parts stores), you can find out what pressure should be by asking here. Make sure all injector wiring is good, and attached to their respective injectors. See if it makes a difference when you disconnect the EGR valve? Plug vacuum hose, and take it for a ride. As far as the high idle at start up -its normal as long as it idles down in a reasonable time-like 5-10 minutes driving in warm/hot weather. Should idle at around 650-700-look for a vacuum leak with some throttle body cleaner. Start engine-let idle-spray cleaner around throttle body, intake manifold gasket areas, vacuum hoses-cracked, dry, EGR gasket area, and around injectors.If you have vacuum leak you'll know- the engine will either stumble, or idle will increase. O2 sensor is the only other thing I haven't mentioned, as you should get a CEL if its bad, or you can monitor them with a BETTER scan tool that has drive cycle capabilties. Hopefully, you could chalk it up to a bad tank of gas, and won't have to do all this checking-BUT why wouldn't you?? Sorry, can't help with the A/C-sounds like you might need a recharge on the freon..
When the truck was brought to me to look at I put my Actron scanner on it because the check engine light was on. About every code could be attributed to vacuum problems. I found 3 vacuum leaks and fixed them and cleared the codes. After restart no check engine light comes on anymore. The truck performs well except for the fact it shakes and runs so rough upon a cold start. After it warms up it runs a little smoother but never idles below 850 to 950 rpms. It also appears to get very poor fuel economy. All readings on the scan tool appear to be tolerable except the rpms are not steady at idle. That is what made me consider the IAC valve. The book says when the IAC wire is disconnected the engine should idle down and if not the IAC is bad. When I disconnect it the engine idles down alright it kills the engine. Is this normal I wonder. I have some sensor cleaner I will clean the MAF and the IAC. I checked the plugs and they looked good and were gapped properly. I just have not found anything that tells me what the idle rpms on this 3.0 should be. I installed a new pcv valve. I disconnected the pcv with the engine running and it seemed to have no effect on rpms or engine running. That seems odd to me. I took some ether and sprayed around all areas that could have a vacuum leak and the engine never changed its tone. I sometimes wonder if the brake booster could have a internal vacuum leak. I pumped the brake pedal several times. That used to let one know if the booster had a vacuum leak but I do not know if that still works nowadays. Anyway thanks for the reply and god bless.
I wonder if someone was playing with the throttle body stop screw-its located in the base plate of the throttle body, and has a small adjusting screw that should never be messed with. I think its there for the techs when making tuning adjustments. Might take a small allen? If you remove the air intake, and look down in the throttle body, does it look like you can see below the plate? I mean, is there a noticeable gap on one side of plate to the throttle body wall? You should not be able to see around the throttle plate at all! It's a very tight tolerance fit, as the IAC takes in the air at idle. If this screw HAS been moved, it can play havoc with the idle, especially when cold. It'll be hard to tell if it has been moved by looking at the screw, if it has not been touched in a while. OK, nuff about that. You said the the idle DIDN'T change when you took off the PCV?? I would pull the hose off (replace if spongy), and look in it for oil sludge built up, and also look where it is connected-the orrifice might be clogged with oil sludge. A spray into the orrifice with some throttle body cleaner might do it-or better yet, remove the throttle body (if this is where the PCV is connected), and you can look thru the plate, like I said above, and you can clean it as is needed. Just some food for thought..
OK, these IAC's are starting to be a maintenance item that everyone should look at when doing oil changes. Remove IAC and clean with some throttle body cleaner, NOT carb cleaner!!
This is only my opinion and cleaning the IAC on these newer models (98-newer) is pointless even though many say it helps. I've gone through so many IAC's on my 2000 Ranger and cleaning the IAC does nothing. Generally just plugs up the little filter on the IAC.
Here are my suggestions for the common problem of fast idle which is consistent of a bad IAC.
First off ignore the Tech Bulletin High Idle TSB 00-3-5 that everyone posts in regard to replacing the connector on the TPS. It will probably fix your problem (1998-2000) but there is a cheaper and better way that don't put the extra cash into Ford's pocket for a **** poor design.
Buy electronic contact cleaner at Radio Shack or an auto parts store. Get the kind that cleans only and does not lube. Also pick up a tube of dielectric grease.
Disconnect both connectors for the IAC and the TPS and spray the contact cleaner on both ends and reconnect and disconnect both several times to clean the contacts. Spray liberally again and again connect and disconnect several times to clean contact pins. Let the connectors hang disconnected for 10 mins so the contact cleaner fluid evaporates.
Fill the pin holes in both connectors with dielectric grease. Don't be scared. Use a lot of the dielectric grease. Connect connectors. This cleans and protects the pin contacts so you don't have to replace the connector as stated in the tech bulletin.
Drive the truck and verify the fast idle has been resolved. You might notice erratic idle for a few mins because of the process the computer has to go through to relearn the idle trim. Best way to relearn the idle trim is to allow the truck to warm up and do some city driving in stop and go traffic. It really doesn't take that long. Don't waste your time disconnecting the battery.
If the fast idle issue returns then replace the IAC
Just an FYI. I bought my Ranger in 2000 and after 36,000 miles my truck had issues with fast idle. I had the IAC and TPS replaced and that lasted about a year. After that point, I was cleaning and replacing IAC's every 6 months because the fast idle would return. In 2011 I started having issues again with the fast idle and found the TSB mentioned. I was so pissed off that I figured no way in heck I was going to give Ford anymore of my money for designing such a crappy wire/connector. I did the above and still drive my truck today (170,000 miles) without idle problems.
Fixed!!!! MY WAY!!!! and screw ford... lol
2000 Ranger XLT Extended Cab with 2.5. 4 inch lift and 31x12.5x15 tires on 15x10 alloys
Thanks for the info. I cleaned both IAC and TPS sensors and coated them with the dielectric grease. The PCV I replaced is in the tappet cover and hoses are good. The clean and lube did not change the fast and unstable idle. Still, I wonder what the idle rpms should be. And should the engine die when the IAC connector is unplugged. A repair manual says the rpms should slow, but it kills the engine on this one. The check engine light came on. I hooked up a scanner to it and the code was for the O2 sensor. I cleared the code and it hasn't came back on. The O2 sensor would not cause the idle problems or would it? Again, any suggestions
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