98 LC. Son was driving it to school today said about halfway there is started running rough...

[COLandCrusher]

98 LC. Son was driving it to school today said about halfway there is started running rough...
Any ideas what would cause that out of the blue? It causes the truck to shudder when you drive it. It goes, but seems to be missing badly, or perhaps exhaust is busted somewhere? sounds bad. completely out of the blue.

 

[Julian Stead]

Coil pack

 

[brianrride]

^^

 

[Sandroad]

^^^This.

It will throw a code that will tell you which one(s).

I assume it's had regular maintenance and that it's all up to date on care.

 

[Dwight S]

As others have posted, coil pack. Driver side front, near battery is cylinder #1, 3, 5 ,7 behind it. Passenger side, near air filter is #2, 4,6,8 behind it. Easy to replace them.

 

[COLandCrusher]

OK, so making sure I get a Denso product correct? And I assume the last 2 of the code that is read is the coil that is bad? when I buy the Denso coil it would not have different part numbers for the different cylinders would it?

 

[Dwight S]

Denso is OEM. Most here prefer it. If push comes to shove, AutoZone has Duralast coils with a limited lifetime warranty. That could get you back on the road until you can order the Denso online to save some money. Then, you could swap out the Duralast for the Denso and keep the Duralast for the next it happens, and more than likely, it will happen again soon.

P0301 is cylinder #1
P0302 #2
P0303 #3
P0304 #4
P0305 #5
P0306 #6
P0307 #7
P0308 #8

 

[COLandCrusher]

Guys, my son is at a place that are looking to plug into the OBD and they are saying they cannot locate where to plug into. advice ??

 

[jLB]

on the transmission hump above the accelerator

 

[flintknapper]

Guys, my son is at a place that are looking to plug into the OBD and they are saying they cannot locate where to plug into. advice ??

Under the dash to either the right or left of the steering column, mine is to the right hand side almost to the transmission tunnel.

 

[DirtDawg]

It worries me when the guys at auto parts stores can't located the OBDII port.... That's basic auto knowledge..

 

[COLandCrusher]

This it?

 

[chrisratz]

That's it

 

[Sandroad]

yes

 

[COLandCrusher]

Thx Guys!! k so had a multiple misfire (p300 I think it was) then 02 Cyl 2 misfire.
So I can get a lifetime warranty Import Parts coil for $83$ but lifetime warranty. hopefully that's all it needs. thanks again really appreciate your swift responses!

 

[labcab]

Rock Auto currently has the Densos for $56 and Amazon has them on Prime for $59. I had two go bad within a few months and went ahead and replaced all 8.

 

[COLandCrusher]

OK everybody, after replacing #2 coil, the car took forever to start, but it finally did, The only issue I am having right now is the rig wants to idle at 200-400 RPM's. It is dying frequently. I have been thinking I need to turn the idle up to about 600-700, but I have no understanding of how to do it on this truck. advice on that would be greatly appreciated. My son has to basically drive with both feet so as not to stall it. It's not stalling every time, but it does stall often.

 

[DirtDawg]

OK everybody, after replacing #2 coil, the car took forever to start, but it finally did, The only issue I am having right now is the rig wants to idle at 200-400 RPM's. It is dying frequently. I have been thinking I need to turn the idle up to about 600-700, but I have no understanding of how to do it on this truck. advice on that would be greatly appreciated. My son has to basically drive with both feet so as not to stall it. It's not stalling every time, but it does stall often.

These 100s use an electronic throttle that's controlled by the ecm. You have another issue that's causing the low idle. I would start by cleaning the MAF and disconnect the battery for 30 mins to reset the computer. Also check all vacuum lines, you could have left one off and a vacuum leak will kill the engine at idle.

 

[COLandCrusher]

These 100s use an electronic throttle that's controlled by the ecm. You have another issue that's causing the low idle. I would start by cleaning the MAF and disconnect the battery for 30 mins to reset the computer. Also check all vacuum lines, you could have left one off and a vacuum leak will kill the engine at idle.

OK, I'll get a electrical parts cleaner on the way home tonight. Once I clean the MAF, how do I reset the Computer? I saw a mention of touching the pos and neg cables of the car together after disconnecting from battery to reset? for a 98 is that true?

 

[DirtDawg]

OK, I'll get a electrical parts cleaner on the way home tonight. Once I clean the MAF, how do I reset the Computer? I saw a mention of touching the pos and neg cables of the car together after disconnecting from battery to reset? for a 98 is that true?

Nooo, don't ever touch positive and negative terminals together. All you have to do is disconnect it for 30 mins and that will reset it.

Also look for any vacuum lines that were left unplugged.