99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

ezbtr · Jun 5, 2007

It just turned 90K, had it since 75K, immaculate service, one prior owner, just started running rough, like a BAD miss, huge loss of power, changed fuel filter 4K ago, has dist 5.7 V8(not coil packs I beleive) bad idle, I'm thinkin NOT plugs or wires, cap maybe? Error flashes 13-24 cycles on dash(Service engine soon) all fluids fine - what the heck could it be? Havin friend drop by tomorrow w/ code reader(cheaper than Good year Im sure), Any ideas? Has ran PERFECT until today, Thanks, Heinz!

Reel Poor · Jun 5, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

At 90K it's due for plugs, cap, rotor, and wires. You'll know more after your buddy runs the diagnostics.

dolluper · Jun 6, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Ouick guess only! fuel pump going south,O2 sensor

ezbtr · Jun 6, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Just dropped at shop, $115 just to put it on tester?? Ouch! I'm thinkin fuel pump or injector maybe???

ezbtr · Jun 6, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Shop says codes mean needs 100K tuneup - plugs wires, cap rotor and injector clean, way too expensive though! Like $600!!! I told them to reset sensor(s) clear codes to see how it runs - I'll do the damn tuneup for lots less! We'll see.....

ezmobee · Jun 6, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Autozone and some other parts stores will read codes for free. Your shop's diagnoses sounds like throwing money at the problem they don't have a clear answer to. Go elsewhere.

dolluper · Jun 6, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Hummm what were the code numbers eh..What code says tuneup time,have I been in the dark for awhile or what.Ask them to tell you the codes,we can help better with them

ezbtr · Jun 6, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Turned out it needed cap, rotor, plugs, wires - plain and simple, I made them show me parts - code was P0300B, they reset code before and it still ran crappy - but boy all the sudden when it just started acting up??? All parts where in definite need of replacing, I had to work from home(not good when new at job, but all where cool w/ it) . Also previous owner had installed Bosch plats, I went w/ factory AC plats, runs perfect now

also got them down in price, $585 for all, damn those caps , wires and plugs are expensive! Would have rather done it myself, but time and decoding weren't on my side. Question: If I had done all(I usually do) would codes reset themselves? Thanks!

ezbtr · Jun 6, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

P.S Cap was def. arcing, cap as well!

SuperNova · Jun 6, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

It's pretty common on those for the injector(s) to clog up. You can try to clean them (special equipment) or you can remove the entire spider (under the intake) and clean it by hand with carb and choke cleaner and compressed air. If they are recommending a tune up it probably means you're getting misfire codes (po300, po301,p0302..etc up to po308) po300 is multiple misfires and p0301 is misfire cyl. #1, p0302 is misfire cyl. #2 and so on. The reason the injector clogs is the hose that connects the fuel fill to the fuel tank rots on the inside, fills the tank with tiny rubber bits which then fill the filter which then clogs and goes into bypass and then they clog the injector or injector nozzles. There is a service bulletin on this; I don't think it ever became a recall. I had a '98 with the same problem. The other alternative is the fuel pump going bad, but they usually whine like heck before they go. 'Course, maybe it's just tuneup time.
--
Stan

Gary H NC · Jun 7, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Man,I'm glad a got family that works at Napa, I just did the same job on my 99 Tahoe, Plugs AC plat.Wires.cap.rotor...Got all the parts for about 100 bucks..

Coors · Jun 7, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Seafoam also.

bruceb58 · Jun 7, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

imported_Coors said:
Seafoam also.

Oh boy another SeaFoam post!

Personally, I would never put the stuff in an engine that has an O2 sensor. I know the website says it is ok but have seen too many times where an O2 sensor gets ruined by oil...and that is one of the ingredients in SeaFoam.

bruceb58 · Jun 7, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

I had a 2000 Blazer that all of a sudden had a check engine light go on. I have the Autoenginuity code reader for my laptop. The codes were for the misfire like SuperNova was talking about. Turned out to be one spark plug with a bad insulator.

There was a TSB on the fuel injection for many years of the GM truck fuel injection of which a 99 Yukon would be part of. Problem was sticky injectors. Was the TSB performed on this vehicle?

Reel Poor · Jun 7, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Here is a copy of the TSB on what type of injector cleaner to use.

Coors · Jun 7, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Dunno, I have 4 friends with fuel injection, including me. I never noticed a difference in a 5.9 Dodge, but they swear by it, in gmc and toyotas.

bruceb58 · Jun 7, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

Chevron makes one or both of the GM Fuel Injector cleaners. I do know that the solvent that is in the Chevron Techron is way better than the solvent(naptha) that is in SeaFoam.

ezbtr · Jun 7, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

I;ve been using B12 Chemtool for years, and still do evey 6 mo or so - did wonders on my 93 Toyota, 5 mph in each gear on a 5 speed! I'll get some more this wknd for Yukon

Seafoam sounds great but I worry bout sensors, if I knew for sure, I'd use it

bruceb58 · Jun 8, 2007

Re: 99 Yukon, Service Engine Soon msg, stumbles, runs rough 90K

I would use that before seafoam. Here is the MSDS on it:

http://www.berrymanproducts.com/Portals/0/BPI MSDS/0216.pdf

If you are tempted to use SeaFoam, just go to Home Depot and buy some Naptha and throw some of it in your tank...will do the same thing.

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