99 Explorer sport shake at low rpm

[J-J]

Hello, Ive been reading around for awhile on many sites and finally chose this one to post on after being unable to locate a similar problem.

I have a 99 explorer sport 2wd sohc with 140000 miles on it.
My truck shakes while idle and on lower rpm usually after a shift @ 35 and 55 until i start to accelerate again.

My check engine light blinks at me while i accelerate then after i maintain a speed it usually stops but stays on.

I got the codes checked at auto zone and i misfire on cylinders 2 and 4.
I also have an evap leak
And my o2 sensors (no cats)

Before the shaking i replaced the coil, wires and plugs about 500 miles after that it started to shake. I resently replaced the plugs again thinking it might have been put in wrong, still no luck.

I dont know if this matters but i also notice a hp drop, i used to be able to peel the tires out on dry concrete and now the truck hesitates when trying to accelerate.

 

[janolsson]

It may be worth double checking the wires are going from the correct terminals on the coil pack to the correct plug.
Below is a guide

Don't laugh as i did this wrong after double checking myself. The truck ran but at lower power and didn't like idling

 

[J-J]

is that even a possibility considering its cylinders 2 and 4? ill still triple check in the morning.

 

[J-J]

Sorry holiday weekend. Didnt get a chance to check yet but any other suggestions on what may cause my problem?

 

[ranger7ltr]

Change the fuel filter after checking the system fuel pressure...After changing the fuel filter, re-check the pressure...See if there is a difference...Then go drive the truck...

 

[joe doe]

pull plugs 2 and 4 and check them .then clean them and reinstall.if it now runs good ,run it !
if it starts misfiring again soon after you may have a head leak.

 

[J-J]

Hmm i never replaced a head gasket before and when i attempted to change the fuel filter it was winter and messing with them damn special plastic tools that you need was to much of a pain. I will clean the plugs and if that doesnt work i will reattempt the fuel filter.

 

[J-J]

So i havnt fixed these parts yet. Reason being my check engine has gone off..
I live in michigan and we started getting cold nights and when i drive the truck cold the check engine light only comes on durning city driving, it blinks at me. once i get on the highway it goes off??? I know it still misfires because it still shakes sometimes at idle and at low rpm. I think i might just take my truck in.. this is getting kinda bazaar for me the way the check engine lights going on and off.

 

[Shanerouleau]

my truck shakes when at low rpms and when at cruising speed on the highway. when i give it gas it seems to be fine. i cleaned the MAF. no fix. i just changed the plugs about 7000 km ago or about 4500 miles i believe. i see no arcing from my wires and the plugs are all tight. i bought a fuel filter thinking that could be the problem but i cant even find the damn thing in the frame rail and if i did find it i dont think theres room between the tank and frame for me to even change it. how is it everyone else seems to be able to change the filter no problem? any help? thanks
oh by the way my trucks a 1998 4 door 4x4 V6 OHV 4.0

 

[bobflood]

My understanding is that the fuel filter is at the frame under the drivers door, not back by the tank.

 

[Shanerouleau]

thanks bob, i found it, now i just cant get it apart/off. heard theres a special tool for it gonna go have a peak at napa after work.

 

[bobflood]

There is a special tool; all of the auto parts stores have them; not very expensive. You have to push it into the connectors very hard, so don't be gentle. Good luck.

 

[Shanerouleau]

got the tool. got the new filter on. makes a difference in power only. still shakes and studders at low rpms and misses when cruising. new battery next i guess since its getting cold out at night, then plugs and wires if that doesn't do it....arrrggghh

 

[J-J]

Yeah this is the same for me. I replaced all the wires plugs and the coil pack. If the fuel filter only gave you a little more power then i might do that because thats half my problem. I sure hope its not a head leak, but if it is, what are the chances of some1 who hasnt replaced this before to do it themselves?

Shanerouleau, if you do end up fixing your problem please post back here with the solution. TY

 

[lugnuts55]

Did you do a compression check? That should give you an idea what's going on. If you don't have a repair manual for your Explorer, you might want to get one. I think you're at the point where you want to see what the compression is. A repair manual will help you. If you know someone who is knowledgeable about engines you might want to ask him to help you.

I had a similar problem on my 96 4.0 OHV engine. I went through everything I could think of. When I did a compression check, I had a cylinder with lower compression than the rest. I bought a head gasket set and pulled the heads. The exhaust valve seats on two cylinders on each head were worn into the head and the valve stem was 7/32" taller than the other valves. Then I found cracks in the head betwen the valves. I had to replace the heads with new castings. The valves and springs were good. I did the work myself but I'm a retired mechanic. The engine runs smoothly now and has plenty of power, not to mention much better gas mileage. I was told this is a common problem but I don't know about the SOHC heads.

Please understand, I'm not saying this is your problem but it could be. It's a lot of work for a beginner or a weekend mechanic. I don't know your skill level but you have timing issues that need to be right or you will damage something and it will be serious.

On a side note, when the check engine starts blinking, it means the problem is bad enough to destroy your catalytic converter and you really shouldn't drive it until you get it fixed. Good luck, Mike

 

[lugnuts55]

This is the post I made when I got it done. I hope it helps some. Mike

05-22-2010, 05:30 PM #14
lugnuts55
WannabeElite Explorer
Milwaukee, WI
'96 Eddie Bauer


Join Date: Feb 2010
Posts: 35


Vehicle Specs

I started this thread two months ago. I have checked and rechecked things during that time. In the process of looking for a cause for the misfire, I managed to fix vacuum leaks so I no longer got codes for lean conditions. I did another compression check, for the fourth time, and got some readings I could use. I found that my compression gauge had seen better days so I borrowed a newer one.
#3 cylinder was the one misfiring according to the code P0303. The left bank was all within 10% of each other but the right bank had 130 on #1, 100 on #2, and 140 on #3. I talked to an automotive machinist that I know and he told me this engine is known for valve seats that wear out and the valve is drawn farther into the head. I decided to buy a head gasket set. At best, I would only have to replace the head gaskets. At worst, well I would find out when I get the heads off. I had done everything I could think of without tearing into the engine so I felt this was the next step.
When I got the right head off, the exhaust valve on #2 was 7/32" into the head. The valve and spring were that much taller than the rest. I felt this was the cause of the problem I was having.
When I got the left head off, I found the same situation but with cracks between the valves.
I decided to replace both heads and do the work myself. It took me about half a day to get them off and about a day to put it back together because of the cleaning. It is running smoother than ever and it even has a little more zip. I will be going on a short trip this holiday weekend of about 250 miles each way so I will get to see how much the mileage improves.
I got both heads for just under $600 and the valves were still good enough to use. There was no carbon in the combustion chambers at all. This engine has over 200k on it. It's nice to drive again and I'm not the last one to leave when the light turns green.
I took pictures of the right head only. I will try to get them here so you can see what I'm talking about.

http://i560.photobucket.com/albums/s...linderHead.jpg

http://i560.photobucket.com/albums/s...inderHead1.jpg

http://i560.photobucket.com/albums/s...inderHead3.jpg

I am not suggesting that all the other posts about misfires will have this problem. This is what my situation was. I also thank all those who took time to read my post and offer a solution. Now I hope the pictures show up.

 

[J-J]

SO my misfire magically stopped.... I didnt do anything except put winter tires on my truck getting ready for cold weather. Kind of strange...