Spark Plug Problems

[Jeff7477]

A while back I pulled the plugs to check and regap, and noticed that the front two cylinders(1 and 5) spark plugs were badly carbonized. I replaced those two with new ones and ran it for awhile. I check again and the same two plugs were fouled and carbonized. Whats going on?

[Rick 91GT]

First-What mods do you have?

Second-What is your fuel pressure and timing set at and what plugs are you running and what gap.

I'll try to help


------------------
Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension,S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon! FIRST TIME OUT 12.16@111 WHEELS-UP

[Jeff7477]

Only Mod is Cat-Back Exhaust. Fuel Pressure and Timing are stock to my knowledge. Run bosch platinum plugs at .050

[Rick 91GT]

Stock.....hmmm well if they are black those two cylinders are running rich or oil is getting past the rings to them, are they wet or just black and cruddy. What do the other plugs look like. It is weird that it is the front two cylinders, what do your wires look like on those cylinders. I am not a fan of Platinum plugs as they do not conduct like a good copper plug. Try swapping to a set of Autolite AP25's for the stock heads gapped at .053. You could also do a compression test to see what condition everything is in, that would be good to know anyway.

[Jeff7477]

They aren't wet, just black and cruddy. All the other plugs look like new. All Wires look the same, fairly good condition. Did a compression check and all were in the 150's.

[andy669]

I'd probably do a leakdown test next. How many miles and what year is the car??

[Jeff7477]

Just about 97,000 and its a 1990.

[juiceman]

while your at it you should just do a complete tear down. its nothing. get rid of those platinum plugs. gap at .040 and drive it. rings, seals etc. have nothing to do with an engine running rich. since its the 2 front cylinders that means that the 2 front runners are getting more fuel/ less air. normal thing on mustangs. does the car run bad? if not, dont try to fix what isnt broke.

[andy669]

since its the 2 front cylinders that means that the 2 front runners are getting more fuel/ less air. normal thing on mustangs.


HUH? Maybe on a carbed engine. On a fuel injected mustang? I dont think so. I'm like Rick91GT, if someone describes the plugs as black and cruddy, the first thing I think is oil.

[juiceman]

well thats what seperates the big guys from the guys who think they know. a black soot on the plugs isnt oil. its fuel. its what is known as fouling. if it were oil well it would be oily. and it would smell like oil. if that is the case then my mistake, but from what was described it sounds like fouling plugs. as for being normal, when yo work on enough motors youll see that that happens alot. maybe not on the few that youve seen. either way, a leak down test isnt needed. unless theres smoke coming from the oil fill or breathers or the exhaust is smoking with a oil smell its not his rings.

[Jeff7477]

Well, its funny that you mention that, because it does smoke. When the car is fully warmed up and been driving around, then you take of the Oil Fill cap, you can see some smoke rise through the tube. I also have Blueish smoke come out of the pipes when I quickly go from idle to WOT. oh, and it burns about a quart every 1 1/2 weeks. Pretty sure its the Valve Guide Seals.

[jimberg]

Jeff, did you try your friend's MAF meter yet?

For those participating, I chatted with Jeff the other night in IRC and he said that he is getting a low voltage from MAF error when he reads codes. He also has stock timing, he believes, but needs to run 91 octane to keep it from pinging.

I told him to replace the MAF since he's getting a code for low voltage and it probably means the computer is running in open loop. Probably rich in open loop mode. I also mentioned that the front two cyinders get less air so will probably exhibit fouling symptoms before the others would.

O2 sensors have never been replaced as far as we know, so I also told him it was a good idea to replace those whether they were the cause or not, although they could cause a richening of A/F ratio.

He also got some fuel pump related codes, but fixed those recently.

I'm with Rick91GT as far as getting rid of the platinum plugs for Autolite 24s and gapping them at .053.

well thats what seperates the big guys from the guys who think they know.

Juiceman, everyone has a right to offer their advice whether wrong or correct. Slamming them because they disagree with you and are probably even wrong isn't really going improve the level of discussion or maintain the level of integrity that this message board has. We all have our level of experiences with issues we have encountered and are willing to share them with people who sound like they have similar issues. Maybe they apply and maybe they don't. It's up to the reader to sort it out.

------------------
351W 89 Mustang GT Convertible

[Jeff7477]

Yes I did try my friends MAF, and the code went away. I went to a local junkyard and pulled a meter of a '91 that was wrecked and now im not getting any codes other than an EVP code which I have figured out.

[jimberg]

That's good to hear. I'd replace the plugs with Autolite 24s gapped at .053" and see if the fouling comes back. Don't forget the o2 sensors, also.

------------------
351W 89 Mustang GT Convertible

[Jeff7477]

Do you know what the part # for those autolites are?

[Rick 91GT]

Well this topic sure has taking off...

First- I asked about the wet plugs because some do not know the differece between a oil fouled plug and a plug that just has heavy deposits on them, I wanted to get a good base line before I started throwing ideas out.

Jeff- The part number for the AUTOLITES is 24, it will be in the upper RH side I believe on the package and you can commonly find these at Walmart.

------------------
Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension,S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon! FIRST TIME OUT 12.16@111 WHEELS-UP

[andy669]

Hey Juice, ya ever have a stock 5 oh on an engine dyno? Oh wait, of course you have, youre a big guy. Well what I've seen from my experiences on the engine dyno tell me that all of the cylinders except #8 all run very close to each other. The egt on #8 has been about 100-150 degress cooler. Thats probably worth 3-4 horsepower on a stock engine. Its amazing how even the egt's on these engines come up. Nothing like a carbed engine where they are all over the place. I'll agree with you on the plug gap, there is no performance gain when you gap over 40. I'll also disagree (somewhat) with Jimberg on replacing o2 sensors. If you know that they are not the problem, (i.e. codes) I wouldnt replace them. They have the capability to clean themselves up. (so to speak) I have watched this happen on my pms. Also if someone is having problems that they cant figure out and they are spending $50 here and $100 there, another $100 for new o2's might be alot. but if someone has the extra $100 to spend when troubleshooting, replacing them is a good idea!

[jimberg]

I believe in replacing O2 sensors since they are the final word on your air/fuel ratio as far as the computer is concerned. If your MAF is off some, the computer will adapt. If your fuel pressure is off some, your computer will adapt. If the o2 sensors of off, the computer cannot adapt since there is no other way for it to determine what the air/fuel ratio is.

As an O2 sensor wears out, it will report on the lean side, which in turn will richen up the air/fuel ratio. Running too rich means fouled plugs. I'm sure his problem has more to do with the MAF sensor being bad, but I still think for a tune-up sake, O2 sensors should be replaced.

Spending $100 every 60,000 miles is a small price to pay for a well running engine.

Jeff, try running a lower octane fuel now that you fixed the MAF. I'm interested in hearing if the pinging goes away. You should also get a timing light so that you can verify the timing.

------------------
351W 89 Mustang GT Convertible

[Jeff7477]

Where can I find these plugs at? Checked walmart and they don't have them

[Rick 91GT]

Originally posted by Jeff7477:
Where can I find these plugs at? Checked walmart and they don't have them

Well Walmart usually has them, you can go to a autoparts store and ask for Autolites 24's they should have them. They usually run a little over $1.00 for each, a lot cheaper then those Platinum's. I change my plugs every 10,000 miles or less.



------------------
Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension,S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon! FIRST TIME OUT 12.16@111 WHEELS-UP