Hey guys, so recently my 99 started running rough after the battery died. I figured the plugs hadn't been changed in ~118K miles so I'd start there. First thing I noticed is that while they were NGK, the old ones only had a single hook to them. The new ones I got were model BKR5EKB-11 and have two prongs.

While changing them out I noticed that the rubber hose/coupler connecting my throttle body to my air filter box was eaten away and had a large hole in it.

I drove the car after changing the plugs and after a few mins it started acting rough again. I remembered the hole in the hose/coupler so wondered if it was maybe that and decided to get an airaid tube figuring it'd also make changing out plugs easier in the future with the stock larger tube gone. Finally was able to install it and unfortunately after a bit of warming up and giving me some hope that this resolved the issue it finally started acting rough again.

I finally decided on using a ODB sensor and found that it was throwing a P0302 which is a Cylinder 2 misfire. Frustrated I cleared the code and on the freeway the CEL started flashing, slowed things down and it stopped flashing but didn't remain on. I finally got home and checked again only to now get a P0300, P0301 and P0302 code. I know for sure I have a P0302 since that code had been on there for quite some time, would the other two be false reads since I'd just cleared the codes?

In any case, what else would I be able to do to try to resolve the problem? I'm thinking I should maybe buy some wires since those were also done 118K miles ago. Other than this airaid tube it has no other engine mods. Any other tips?

 

My vote is your injectors are dying.

does the problem get worse when the engine is warm? And then drive fine the next day cold?

 

Agreed, i've seen them act flaky cold hot and in-between intermittently making it very difficult to narrow down without actually pulling it apart and swapping the effected cylinders/injectors flagging misfire. These brown plastic 99'+ "updated" injectors really seem to be showing there age after 20 years, I haven't seen any reports of 96-98's having this problem. Could also be the wire harness from injectors to ECU or an ignition issue since we don't know what your vehicle history is, or the quality of parts and service it received.

 

It's random, for the most part it will drive fine but randomly it'll start shaking for a few miles then be fine again.

 

When it’s “shakin” is the CEL blinking?

 

No, the blinking just started yesterday and wasn't consistent, it'd only blink on the freeway and only on WOT. When at a light or stop sign, if it decided to shake, it would not blink or give the CEL.

 

CEL flashing is random or multiple cylinder misfire P0300, its telling him he has severe misfire and it needs to be addressed, it will shake if only one cylinder is misfiring, either ignition component, injector(s), intake leak, temp sensor or wiring. Hard to feel misfire above 2000RPM's if its only 1 cylinder and then the other cylinder intermittently like these injectors tend to do, might feel sluggish depending on throttle position, gear, or load, might feel shaky while at idle, it really is a PITA to figure out, but after all other avenues have been combed over and checks out good, then the decision is to drive it like this, let the ECU flag the offending cylinders leave the CEL on and decide if your going to do all the injectors or just the offending cylinders that put out a code.

 

Thanks, this is what I was really wondering, if my having cleared the ECU had been a bad idea and needed to let it "settle" on a particular code or not now that it had been cleared since the CEL hasn't decided to stick yet.

 

Yes, you need to let the CEL do its thing so you know what cylinders are causing you grief, sometimes codes are pending until it recognizes it as a issue and tells you what's cylinders are misfiring. Check the CEL after it's been doing it for a week or so (depending on how much you drive)during your normal driving routine. You don't wanna swap 1 injector to find out you have another on the same fuel rail you just pulled. Or ya say the heck with it and swap them all with all new rubbers. I think if I have this issue I might swap the 96-98 injectors in, I think the updated ones are more problematic and I don't see a difference in gas mileage from the 97-99 to justify the "update"

 

Is there any additional hardware needed to put the 96-98 injectors in?

 

You should replace the middle plenum gasket when you split the upper and lower intake runners, but when I was tracking down my injectors I opened it up so quickly after replacing gaskets that I would do 2 or 3 crushes before I replaced them.

mine was particularly stubborn as I got a DOA injector when I bought my reman set.

 

I assume you would need the corresponding o-rings and insulators but those to could be the same, a parts search will confirm this when ordering.