99 SR5 running rough

[TheHolyMoly]

Hello, I have a 99 SR5 V6 with 215,000 miles that within the last couple of days has begun to run rough.

Two days ago it was running fine until I came to a stop, at which point it almost died and began running rough and underpowered, like one of the cylinders was not firing. I thought maybe it was from low fuel and fueled up. When I started it back up it ran fine for the rest of the day.

Yesterday the same thing happened, I was coming to a stop and it tried to die, then began running rough and underpowered. I pulled into a parking lot, turned it off and back on and it ran fine.

The first couple of trips I made in it today went without incident, then after letting it sit for a few hours I was going to run another errand but when I started it it was running rough right off the bat. At that point I changed the plugs and wires but it did not fix the problem. I also noticed that there is a slight gasoline smell.

Can anyone tell me what's going on?

 

[scrhew]

Mine did the same when I first got it. Have you cleaned the MAF and Throttle Body? If not this could be your problem.

Heres a good write up on it with a link how to clean the MAF too.

http://www.top4runners.com/ja/cleantb.html

 

[TheHolyMoly]

I'll give that a try, thank you.

 

[TheHolyMoly]

In the mean time I pulled the wires to the plugs on the driver side and started it up. There was no difference when I pulled the wire closest to the driver and the middle wire, however when I pulled the front wire it started missing and sputtering.

Could this mean that the coil packs to those two closest the driver are bad?

 

[scrhew]

I have no idea, that is something thats over my head on that one. If i thought some of my coil packs or wires were bad I'd just change all of them at once.

 

[the great him]

ok so if you think you have a bad coil pack(or two), swap one of them with the one you think is good, and see if the problem fallows the coil pack. my guess is it wont. if it doesnt then your try that once again with the remaining coil pack, to eliminate the coil packs as the issue. once this is done and if the problem stays and did not move, next go to the fuel filter, and swap that out with a new one(under $40 at the dealer and thats where i would get it from -i have heard bad stories about some generic filters having messed up threads or wrong thread pitch, or even missing the seal washers ect...) put the new filter in and see if that fixes the issue, even if it does not, its a good idea, especially if you dont know the last time it was changed, they dont last forever and can pug up and restrict fuel flow. the next step if the problem is not fixed is playing the swippy swap game with the injectors... the two cylinders that had the miss fires, swap the injectors with other "working" cylinders to see if the problem remains or fallows. -i personally think this is probably where you are going to find the problem at. -be carefull with the O-rings on the injectors, make sure they have some lube on them so you dont tear them putting them back in, some sil-glyde will do the trick. if that still doesnt fix the issue id do a compression test, but still i dont see why you would only have this issue part of the time if it was a bad valve or rings or a cracked head... while your at it, check the codes in the ECU -do you have, or have you gotten a "check engine light"(CEL)? if so, find out what its saying and report back

 

[TheHolyMoly]

Fixed/follow up

Ok I bought a new coil pack to trouble shoot with but also decided to change the PCV valve, I believe the PCV valve was the culprit as now it runs great. FYI.

the kid, thanks for the advice, PCV valve seems to have fixed the problem, there was no check engine light and I did not get around to taking it anywhere to get the codes.

 

[TheHolyMoly]

Update. It ran fine long enough to take it out, drive it around the block, wide open throttle, came back and parked it for about an hour, started it and it's back to idling/running rough.

Next step clean TB/MAF?

 

[the great him]

id check your tire presure

 

[TheHolyMoly]

All 4 tyres were good, however the spare was 1 psi low so I put some air into and it runs great now!

Thanks the kid! :clap2:

 

[the great him]

you could go ahead and replace the air filter, and or clean the MAF, but with your earlier test with the spark plug wires, i really dont see the air being the issue, if it was, you would have the miss at all the cylinders not just one or two, i think this is either a spark or fuel issue. thats where you need to look. you said you bought a new coil pack, what brand? denso? bosch?...? and for what its worth you didnt need to buy one just to check or diagnose, i just would have swapped a known good one around to the suspected bad one and either confirmed or denied the problem... but please refer to my earlier imput about fuel filter or injectors. you could also have an issue with the fuel pump, this sounds familiar to problems ive experienced with other vehicles when the fuel pump goes out or starts to go out... it works fine when cool but run it for a while and it heats up and starts acting up and eventually it will just flat out stop pumping and leave you dead where it dies...

 

[TheHolyMoly]

I've got my eye on the fuel filter, I added some injector cleaner for shits and giggles. The check engine light finally illuminated so I took it to AutoZone and found #4 was not firing, I swapped my new coil pack from 6 to 4 and now it runs fine...although it idles at 1300 rpm in park, I think this is due to having a clean MAF so I'll pull the EFI fuse and let it reset. When/if the problem returns I'll change the fuel filter.

Thank you.

You wouldn't happen to be Billy?

 

[the great him]

if your asking if thats my name, nope