Hard Starting/Rugh Idel not IAC..... any help???

[Roger84]

All right guys I just replaced my IAC in my 98 sport SHOC, as was suggested by the community, in hops of curing my rough starting problem. What happens is when I try to start “cold” the engine starts, idles rough for a sec then dyes. I have to hold gas pedal down 1/3 or so the way down (3000rpm) for sever seconds then everything is fine… from what I have read and have been told, it sounds just like an IAC problem but with a new IAC installed the problem still exist… any suggestions???… aside I halve also experienced a bad hesitation two separate times in last 4 months while flooring my explore off the line… I have not though much of this just contributed it to bad gas. But I am now starting to think it may be related… any suggestions would be appreciated thanks guys

 

[Hoppy]

Are you getting any CEL codes? Is your fuel pressure ok?

 

[Roger84]

My computer is clear any of codes. But i have not checked my fuel pressure... or for that fact changed my fuel filter. Witch I need to do… I’m at ~120,000 miles, ~57,000 are mine and have never changed it…..

 

[Hoppy]

I would change it if I were you. Reason being is you will eliminate the fuel filter as a problem later as well as now. My old Bronco II did that just after I bought it. I got it on the highway and opened it up and there was little power to get up to 100kmph. It held there once I got it there but it was quite tempermental in keeping the speed.

 

[Roger84]

My problem only occurs once a day, which is the first time I start it. After that it’s good to go the rest of the day. But the gas filter is next to be replaced. Just seems to me that if it were the problem it would be a persistent problem and not a come and go one….

Does anyone know how to easily check the fuel pressure on the SHOC? (Links ok)

I have also read that the MAS, or maybe the intake manifold gasket, could cause this problem.

Anyone else have similar problem with a solution????

 

[Hoppy]

I would start by checking the fuel pressure. You can get a fuel pressure gauge at any automotive supply store and find the schrader valve on your fuel rail. the gauge then screws onto this shrader valve connection. When the engine is cold when you have the problem, turn your key to on. Now check your pressure. Check the service manual to see what the pressure should be. I think it should be around 40 psi, not 100% sure. Start your engine and see what the pressure is. The pressure will drop when the engine is idling. As you rev your engine the pressure will climb up. You can also check your fuel pressure regulator by taking the vacuum line off of it. This will simulate a full throttle position because there is no vacuum applied to the regulator. Plug the line back onto the regulator and the pressure should drop back down again.

If you have very low pressure during the first check with the engine not running, but ignition on, then I would try changing the fuel filter and check the pressure again.

One other nice thing with the fuel pressure gauge is that it usually comes with approximately 6' of hose hooked onto the gauge's pressure releif valve. You can use this gauge to releive the fuel pressure in your system so you won't get sprayed from head to toe with fuel when you remove the filter.

I am not sure if this is your problem, but I would start there with the fuel system. Eliminate the cheap and easy stuff first before changing all kinds of expensive sensors and major gaskets which require major engine tear downs.

 

[Roger84]

I replaced my fuel filter yesterday, a bit of a messy process that is. Popped the new one in and checked my fuel pressure. Pressure was good right around 44psi at idle.

I was hoping this would fix my problem do to the fact that the filter was quite clogged. But this morning when I started her up same rough idle for about 15 - 30 seconds.

I guess the next step is to check the MAS and then the intake manifold gaskets….

I’m running out of ideas

 

[Turdle]

Throttle position sensor?

 

[Space Truckin']

Replacing the lower intake manifold gaskets with the new and improved Ford part solved this problem on my ’98 SOHC. This very simple and inexpensive repair was identified in a TSB. You don’t always get a CEL/MIL because typical intake manifold gasket leaks are masked by engine electronic adaptive strategies, so they just show up as drivability (or starting) problems. If the leak is bad enough you could see DTC P0171 or P0174 but the absence of these codes does not mean the gasket is not leaking. (Substitute P1131 or P1151 on Natural Gas Vehicles.)

 

[mountaineer99]

1999 mountaineer won't idle cold

Space Truckin I read your post on replacing intake manifold gasket on your 98 I have the fault codes p0171 and p0174 and have replaced the 4 oxygen sensors and the mass air flow sensor and believe I have the same problem.
How did you determine the intake manifold gaskets were the problem?
you mention a tsb what is that?

 

[Space Truckin']

A TSB is a Technical Service Bulletin. It is an internal memo that Ford uses to tell all there repair techs about the solution to a common problem. In this case, they redesigned the gaskets so I used the new Ford part from the dealer. Ford troubleshoots intake manifold gasket leaks using a propane probe. (Hank Hill would be proud.) You can do the same thing using something like ChemTool (Berryman B12 carb cleaner). The idea is to spray around the base of the manifold and see if the idle changes. This would indicate a leak. Frankly, the test is more trouble then it is worth and not 100% reliable. It is easier to just replace the gaskets. You may need to lightly smack the upper manifold to get the EGR to pop out. Remember this is a plastic manifold so the bolts require very little torque when you reinstall them, and be careful around the fuel rails. They are not very strong either.

 

[Space Truckin']

I just looked at one of the TSB’s and Ford now uses a smoke machine to test for intake manifold gasket leaks. While this is a more reliable test, it is also much harder (or impossible) to duplicate at home.

 

[Roger84]

Thanks for the input. So what do I ask for when I go the dealer? A lower intake manifold gasket set?

About how much should I expect to pay? Does any one know a good post on here on how to replace the gaskets?

 

[Roger84]

Man I have got to say this it a grate place to get advice for my explorer. I can always count on everyone. Thanks

 

[Hoppy]

Roger 84,

This is a great place for the Ex! I wish I could find such a place for my Olds Intrigue that I just bought. There is hardly anything out there for it because it is not a car that was mass produced. I have received alot of help here on this site, as well as giving alot of help. Explorers are relatively simple in design and are a typical Ford as such. I have owned 5 Fords in my time and only one VW, which was very cool (75 bug) and now the 02 Olds (my first GM product). The explorers are quite reliable. I have had nothing major go on mine except for my 92, but persisted on the ex's because they suited all my needs and did not want to try a GM because of them not running correctly unless the check engine light being on, or a Chrysler/Jeep because they were all rattle traps. The only thing killing me now is gas mileage and plastic that cuts the paint to the metal and starts rust. The ex's are not good on saving gas. Unfortuneately, I am thinking of selling mine this fall because of it. I will definately miss her if I let her go because like I said, she suits all that I need in a vehicle.

As for a smoke test. I think that is nuts. An engine should not need a smoke machine to find a leak, nor should it leak period. Just goes to show you that Ford is keeping up with GM and Chrysler in crap IMHO. To be perfectly honest, I would purchase two Japanese or German vehicles to replace my Ford and GM, but they are too expensive to purchase up front and parts prices are rediculous. Not to say that a Bronco II alternator only costs around $50 and a 92 Explorer alternator costs $250. (Canadian that is).

AHHH, VEHICLES ARE A MAJOR RIP OFF!!! Where's my horse!

 

[Space Truckin']

I don’t remember the exact cost of the gaskets but it was just beer money, and not even good beer. The lower intake manifold gasket is also available as part of a kit that includes the revised timing chain tensioner. See TSB 00M12 if you have not dealt with that problem yet. You could kill two birds with one stone.

 

[Calixto]

Iac

What's an IAC?

 

[Space Truckin']

Idle Air Control

 

[Roger84]

Last night I finally got around to replacing the intake manifold gaskets, both upper and lower, on my explorer last night. The whole procedure took me about 3 hours. This morning there was no rough idle. Though the rough idle is hit and miss so I will give it a few weeks to ensure this fixed the problem. I hop this fixed it. The old lower gaskets did show signs of leaking and were rather hard.

thanks for the help everyone

I hope this thread can help other people in the future. I will post a definitive answer to weather or not this fixed my problem.

 

[Roger84]

truck set for two days and started up without any problems. looks like the problem is fixed

thanks to all