Shuddering at idle in 98 XLT

[Nemo0101]

Hi all,

I have an intermittent shuddering in my 98 XLT SOHC while I am sitting at idle. Sometimes it is barely noticeable like a slight vibration that comes and goes but other times it really starts to shake and rattles my CDs in the center console and anything else loose in the car. Of course the garage says they can't reproduce the bad shakes and they feel the light vibrations are normal. I've owned the car for 7 months and the shuddering only started about a month ago. It does not matter if the engine is hot or cold. It usually cycles through 1 or 2 times per minute. I can't notice it once I'm moving or rev the engine. We own another 98 XLT no problems.

Other notes:

Since I have had my car I've needed the following repairs:

Throttle body replaced (recall)
Cam belt tensioner replaced (recall)
Timing belt tensioner replaced (broken)
Front axle seals (replaced, twice!)
Pinion seal (replaced)
Lower ball joints (replaced)

The truck is at 35700 miles so the warranty is almost up. My car has been in the shop for one thing or another for almost 20 days over the last 3 months. It still has a whistling noise under acceleration along with shuddering at idle. I'm starting to get concerned that this thing is a lemon.

Maybe I'm over sensitive after owning a number of Jap. sedans that never had any problems, but this is ridiculous that I should even worry about a 2.5 year old truck with less than 36K. Any thoughts would be appreciated.

 

[Stephen]

Well Mike, you should start by cleaning your MAS (Mass Airflow Sensor) to help with the rough idle, the instructions can be found in the FAQ. As for the whistling at acceleration, if its pretty faint, its normal. The fuel pump or some other fuel related component causes that noise. Mine does it too, and always has.

As for reliability, I never had any repairs on my truck until 70,000 miles, then it kinda took a crap on me. Now that everything but the ball joints are done, its running great again.

You might very well have a lemon.

Welcome to the site and good luck.

 

[Gage]

I to have this issue

It shimmys and idles funny, Yes during speed it will not happen. I have tried clean the MAF and have to do so on a regular basis. Every 5k Miles. it seams to do it more as it heats up and the idle adjusts to about 600 rpm. I have a diff. prob though, my X will die when it is really cold under 10 deg. I will have to start it two or three times before it gets going in the morn. Anyway when I clean the MAF it will idle higher in the 800-900 range after a couple k miles it will go back to the shimmy!

 

[Nemo0101]

Please forgive me, but I know I'm suppossed to look really hard with the search function but could someone bring a post back up that really explains how to clean the MAS. Others may benefit from this as well since it seems to be the first stop in troubleshooting a problem. I've found numerous posts saying to clean it, I can't seem to find one that says what exactly should be cleaned in it and how. I think I located it in my truck (the next piece after the airbox) but what exactly do I do with it. I don't remember ever needing to clean such a component on my other cars is this unique to Fords or Explorers? BTW, my explorer doesn't see much dust (i live near the city). It is pretty much used to haul friends, Scuba gear and a 2000 lb boat (as well as me to work everyday!). I did reset my computer tonight by disconnecting the battery and I noticed it seemed to run a little better, but I still have the shuddering after a few minutes.

Thank you for you help and responses!

 

[SplashMan]

99 XLT SOHC 42K

I started to get that shuddering/ruff idle this winter on my X and I dumped a bottle of STP in the gas tank for two fill-ups, and then I ran some 93oct through it(normally use lowest). It took about two weeks, but the shuddering quit and the idle is low, but not ruff any more. Hope this helps a little.

 

[Gage]

The url for that is http://www.4x4central.com/tips.htm#mas

It will tell you how to clean it. It does not matter if you live in a dusty airea or not.

It is in the tips on the main page.

PS the right tool for the job is best!

 

[Nemo0101]

Great responses. Thanks for the info. I'll try MAS cleaning procedure this weekend and maybe the fuel treatment if the rough idle persists.

 

[yob_yeknom]

Originally posted by Nemo0101
I don't remember ever needing to clean such a component on my other cars is this unique to Fords or Explorers?

From what I hear Ford 4.0's are notorious for needing them to be cleaned. All the mechanics around here seem to say that. As for why, I do not know.

About the fuel treatment, make sure to get the complete fuel system treatment. It has worked wonders for me on all 3 vehicles I have owned.

 

[Lowrider]

Hi Mike,

I had my tranny rebuilt on my '94 XLT. After a few days back from the shop I also noticed a slight shudder at idle that didn't seem to be there before my trans died. It also seems to cycle on and off over the course of a minute or two. I've read some posts about changing the trans fluid to synthetic since the shop didn't use this when they rebuilt it. To me it does feel like the trans shuddering, but I am going to clean the MAS and run some new wires and plugs this wekend. Hope this helps.

 

[JoelF]

Hey Mike,

I had the similar vibration and pulsing at idle with my '98 XLT. I brought it back to the dealer a couple of times for this. At first they acted like I was crazy but I was pretty insistant about getting this fixed after spending 30 grand for this truck. Finally they told me that there was a TSB on this problem, specifically for the 4.0L SOHC engines.

The problem has to do with a resonating frequency that occurs at idle when the engine is running a certain Rpm's. It has something to due with the resonation frequency of the exhaust system as compared to the engine Rpm's. How they determined this, I don't know. They ordered a recall kit that included several custom brackets for the exhaust system and other contact points in the general area.

Once these brackets were installed, all of the weird vibrations I had at idle were gone except for a minor one that is felt for a couple of minutes during warmup at high idle on cold days. Once the engine warms up, there is no vibration at all.

Go to the National Highway Traffic Safety websight to get details on this recall: http://www.nhtsa.dot.gov/.

I hope this helps.

JoelF

 

[Gage]

Joelf

Thank you for the unput! I will check this out

 

[Jon_Herr]

TSB on intake manifold seals

I didn't see it in your list of things that have been done, but there's a TSB for intake leaks for your year. Might want to get it looked at.

There is a TSB for the groan and shakes you are experiencing. I haven't had mine done yet but like it was mentioned earlier it's a braket for the exhaust, new power steering pump hose, and a new program for the PCM.

If you ever develope a whistling at idle, there's a TSB for a new separator plate in the transmission.

I don't know what is wrong with the '98 model year but it seems to have had a lot of corrective actions issued against it.

Good luck,
Jon

 

[Jon_Herr]

TSB Details

If you check my other posts you'll find details on the TSB's that I have mentioned.

Jon