Hello,

I have a 2000 Ranger, V6, 4.0L, 4x4. 90,000 miles.

I am having a problem at startup, with a miss. It only lasts for a few seconds, then everything seems fine. It also only does it on a cold start, not when the engine is warm. Basically, it runs really rough for a couple seconds, the RPMs are low by a couple hundred, then it catches and runs fine. It does it 9 out of 10 times if it is cold. After it starts running normal, everything seems good on acceleration and higher speeds. If I give it any gas while it is running rough, it doesn't help, just starts bucking faster.

Last week I got a check engine light, and it came back as a miss in cylinder 4. There was no noticeable miss at the time, and it hasn't come back on since it was reset. I assume it is from the same problem.

I changed plugs and wires, which didn't help. The only other problem I had, was an issue with the IAC. Totally different problem, which was resolved by cleaning the IAC.

Any thoughts on what it could be? Could the IAC be acting up again and causing a different problem? I'm at a loss with it only happening at a cold start, and only lasting a few seconds. Thanks for any help.

 

One more try for help.....

Someone told me they thought it was a bad or clogged injector, makes some sense.... I'm not sure though.

 

I would start by checking the fuel presure at cold start-up. If you don't have a presure gauge try cycling the fuel pump a few times by turning the key to on, the fuel pump will run for a few seconds, then turn the key off, do this several times and see how it starts.

Has the fuel filter been changed?

 

I will try the fuel pressure. The fuel filter is still the original, maybe I should change that too. Thanks for the reply!

 

I would seriously look at the IAC if you've had problems before and only cleaned it instead of replacing it. Here is a link to the sticky for checking and replacing the IAC. It only takes a few minutes to check if the IAC is bad, so I think it's worth checking. https://www.ford-trucks.com/article/...r_IAC_Fix.html

Good Luck

 

That fuel filter is WAY past due for a change & should be done, if for no other reason than to relieve the pumping strain on the fuel pump.

I like the idea to replace the IAC too, if you've had problems with it, as cleaning it successfully & having it last, is a MAYBE thing!!!!

I'm not clear on the cyl 4 misfire though. Has this code shown up since you replaced the plugs & wires, or was it there before they were changed????

 

New fuel filter going on tomorrow morning.

As far as the misfire... The misfire on cold starts began before I ever got a CEL. Then I got the CEL, I think it was because I tried to accelerate while the miss was happening. Since changing plugs/wires the light hasn't gone on, but the miss is still there.

The 2 cold starts I had today, I tried the turn the key on and off a few times method, and I did not get the miss. I'll have to do it a few more times to see if it still doesn't happen, but I haven't gotten two good one in a row before. I'm not sure what that tells me, but at least it tells me something. Maybe it tells you something?

As far as the IAC, I'm still considering it, but the problems with that were totally different. On deceleration, the rpms kept dropping until it almost died, and then picked back up, and the rpms were low on startup. Both of those problems are still good, which makes me think the iac is still working. I will look at it though.

Thanks for all the help so far.

 

Well the "turn the key on & off a few times" is sort of a clever low tech way of determining if the problem may be fuel pressure/delivery related, sounds like it may be, with the 2 successes you've reported.

We'll have to see if the fuel filter change is the root cause, or if the pump or fuel pressure regulator are acting out. I hope a fuel filter change will fix things up.

You'll likely need a release tool for the fuel line to filter fitting, so check out what you'll need at the parts store when you purchase the filter.

 

I have a 98 4.0 and I have the same issue with cold start ups, actually not always cold, even if it has sat for 4-5 hours. After reading this post I went out and cycled the key on and off, and it started with no missing.

I have already changed my fuel filter a couple a months ago, so I know that is not the problem. I changed it because I got a 1151 code, and that was one of the easy fixes on the list. It didn't get rid of code.

After reading this I'm thinking that the missing at startup and my 1151 code may be related. The CEL is off now, but will probably come back on, and Autozone will confirm that it is 1151 again.

Are the most likely problems either the regulator, or the fuel pump?

 

On your '98, the regulator is in the tank with the pump, it's not on the fuel rail.

A fuel pressure test would be worthwhile, if at all possible.

 

Thanks for that info, I was looking under the hood to see if I could identify the regulator, I would have looked a long time. My Chilton's manual is currently hiding somewhere, so I couldn't reference that.

I just read my post again and noticed that I should have put the word fuel filter in when I said I changed it. That is what I was referring to.

My CEL just came on again. And I noticed that when driving the truck feels like it is hesitating, or bucking slightly.

I will have to find my Chilton's book and see if it states how to check the fuel pressure.

 

The new fuel filter did not help the problem. It does not miss when I turn the key on and off 3 or 4 times before starting. I guess that tells me it is somewhere in the fuel delivery system, but now I have to figure out where somehow.

Thanks for the help so far.

 

Have you checked the fuel pressure as Ken suggested???? If so, post the numbers.

 

Thats bizarre. I am having the EXACT same problem. Every time that I start my 98 b2500 after it has cooled off, it idles extremely roughly about 500. I depress the accelerator about half way and hold it there. The engine "bucks", jumping from 500 to about 2000 rpms about 5-6 times before it can finally break 2000. Then everything is pretty much OK, except that sometimes on the highway the fuel pressure seems to cut out for a split second. (rarely happens) I am going to try the key on thing a couple of times, and I will post the results. I have already changed the TPS, Plugs, cleaned the IAC and had my friend run a diagnostic on it. NO ERRORS???? Thanks for listening!

 

HAWKI-PEERS have you figured your problem out? or anyone else I have a 1998 4 cyl does the same thing runs bad on cold start up and sometimes will fall on its face for just a second going down the highway. I have checked fuel pressure old fuel pump 105 new is like 90 psi seems high to me.