Detonation problem 97 T-Bird with 4.6 V-8

Recently, the engine began "pinging" when shifting into high or overdrive, especialy with AC on. I tried using higher octane fuel inclding premium but it seems to have gotten worse. Just 2 days ago, the service engine light came on. Can't get into the garage until sometime next week so went to parts store and the code was read as "(fuel) system lean - bank2" The store rep said the code was coming from the o2 sensor meaning the one side of the engine was getting less fuel thna the other. Is that correct? Is there a process to diagnose the problem. Will geting the injectos cleaned resolve this? Any help would be appreciated.

i would try some injection cleaner first, but injectors CAN go bad.

Well, finally got the 'Bird into the shop and the code PO174 was still in the system. Ford has a list of 30 some repairs or checks to make for this code and the shop owner said it could cost $1,000 to check all of them and we still might not find out the cause. The scanner also reported that #2 spark plug had not fired 4,000 times, so they replaced that plug, and suggested that the plug wires might need to be replaced. Car has 62,000 miles on odometer.

They cleared the code and sent me on my way. The pinging has not improved any and the SES light came back on yesterday while I was on the road. Taking it back today to see if the same code is in the system. I have also ran 4-5 tanks of fuel with Lucas injector cleaner in since the trouble began.

Any suggestions?

pakus, ramrod, anybody,
Doesn't this sound like the ignition is too advance. Isn't that caused by the load on the engine, measured by either the MAP, or MAF?
I've seen O2 sensors cause lean problems and set no code. They would linger within spec, but at the upper end (.9-.7V) causing lean condition but no pinging as I recall.

doc, You really need a scantool to watch different parameters. Bank2 lean, I'd watch o2b2, maf or map, fuel mpulse 1 & 2, spark advance, and TPS. Hard to say whats wrong with your bird. Helpful somebody seen this very thing and give you a better starting point.

Catfish you are on the right track. The pid to monitor is the BARO pid. It is a calculated value made by the MAF. Here in Texas a good reading is around 150 to 158 hz. If it drops into the 140's range it will begin to run lean. Less hz means higher altitude which means less oxygen so the computer adds less fuel.

YO !!!!! ( man that was a good nap ) Ah,, yea, Yea seems that summer time here in Florida the ole PINGER gets worst as the Temp climbs an the air burns your throat ( ever notice how nice your engine sounds when its raining an its like 70 degree's ), I gotta agree with the timing aspect. I have a very dear lady customer she's like 82, Drives this ole 87 Merc. Grand Marquie, a tad over 68,000 miles . She was by this week , Saying She thought the squirrels had gotten in Her motor ???,, Anyway Iam sure you guys have heard or possibly used " SEAFOAM ", well I ran a can of it through the motor, an yea it smoked like the dickens for a bit , Changed the plugs , no more pinging an got a pass 11 after reseting memory an test drive ,,So we sent her home. ,, My thinking is it possible had a lil bit of carbon build up, that led to the pinging

Thanks to everyone who replied - you guys lost me with some of that technical talk, like pid and hz, but I will print out your responses and share with the garage guy. He is a pretty decent mechanic and I trust him not to rape me.

I am not completely without mechanical experience but all of these computer controls make it so a shade tree can't fix anything anymore.

The pinging is worse with AC on which creates a load on the engine, and the engine temp seems to be higher than normal, but so far I can't tell if the temp increases come first or the detonation is causing it. The 'bird will run ok at highway speed so long as I can maintain throttle position. If I have to slow down for traffic, the spark knock will begin while trying, ever so gently, to accelerate. When in traffic, or at lower speeds, I turn off the OD to keep the trans from shifting into D or OD which increases the spark knock. I thought about the timing issue one of you mentioned, but there is no way to set that anymore, except by computer, is there?

Again, thanks to all for your help. If the additional info means anything, I'll be glad to listen. If / when I get it fixed I'll share the details in case anyone else has the same problem.

By the way, no one answered whether chnaging plug wires would be a good idea. What do you think?

Its a good idea, but I don't think its going to fix problem.

I took the 'Bird back to the shop today and the same code PO134 was in the computer. The mechanic did find a small vacuum hose behind the intake which was cracked and replaced it. The pinging seems to have decreased, but the temperature was only 67 degrees instead of 105 and the AC wasn't on. I'm going to drive it some more to see if the code comes back.

How about this - one of the guys on another forum suggested putting in Ford OEM sparks plugs - he says this corrects the problem. Interestingly, the former owner replaced the plugs at 47,000 miles and I bought it at 53,000.

Have any of you guys heard of this fix?

Great let us know what you find.
As for the plug thing, can't hirt. As I remember Ford Contour 4L had 2 different plugs. My guess is that 2 cylinder shared one coil pack. As for as replacing plugs 50K or 100K, I don't on mine, I wait until something breaks, 137K on my Ranger orginal plugs as far as I know.

Chapter 3 - after driving on longer trip, SES light came back on. A suggestion on another forum was that replacing plugs with genuine 4d plugs would solve the problem. Back in the shop today, and replaced all spark plugs with Autolite (plugs that came out were Motorcraft with about 17,000 miles on them.) Rechecked for vacuum leaks and none found. Checked EGR for proper operation and found OK. PCv checked and found OK. We have checked virtually everything on the computer diagnostic list for this code. Oil overfill and oil dipstick not seated are 2 of the diagnostic checks for this code. Drained oil and replaced with 5W30 Amsoil (previous owner used 0W30). Made sure the oil was not overfilled and dipstick seated properly. A few other checks made that I forget.

Still pinging though not quite as bad, but then again it gets worse when it is hot. Next week, the shop is getting a new piece of equipment that will clean intake, manifold and injectors, and my mechanic volunteered my car as the demo to see how well this new machine works - I only have to pay for the materials.

Any other ideas?

I was really hoping that changing the spark plugs would do the trick, but...

I see I made a typo on one of my prior posts. The trouble code is PO174, not 134 like I typed a few posts back. Must'a had a few Millers in me then.

P0174 System too Lean (Bank 2)
P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)

My guess is that O2 sensor 1 bank 2 is always showing lean or a < 0.4V. This may cause the computer to compensate with more fuel, and not see a change in sensor output, causing the code. This lean condistion may also cause computer to advance ignition timing causing your pinging.

It seems the problem may be caused by the O2 sensor (of which I understand there are only 4 of them). I guess that will be the next thing we try if the cleaning of the intake and haeds doesnlt seem to help.

I was an OK shade tree mechanic but I lost touch with all of these computer controls, but I had a sneaking suspicion about the O2 sensors from the beginning.

Will stay in touch and keep everyone informed. Hopefully it will be fixed soon.

Next chapter - next trip to my local garage, we had the injector system cleaned using BG chemicals (I forget the names of the materials), flushed the transmission and cooling system (the last two just routine maintenance - nothing to do with pinging) and replaced one of the O2 sensors. After that, it seems the pinging got worse.

So I finally caught up with a friend's son, Lee, who works at a local 4d dealer and he checked the car with a 4d scanner. It indicated the mass air flow sensor was bad, even though it had been replaced by the former owner about 10-12,000 miles back. (maybe the former owner was having the same problem). The scanner was reading the car's system of baromtric pressure reading at 128 and it should have been 156 which Lee says will cause the system to run lean. ANyway, the MAF costs something like $325 to replace plus the $120 the dealer would charge to use the scanner, so Lee is going to do the job on the side. He thinks he has a spare we can try with having to buy one to see if that will solve the problem.

Next chapter:

After having the T'Chicken scanned at dealer last Tuesday, I drove it to Western MD (400 miles round trip) on Thursday and around home Friday and Saturday. Got in this morning (Tuesday) and it would start but not run. FInally gave up and jumped in the trusty old AStro and headed out for 250 mile trip. (Ironically I bought the "chicken" to save mileage on the Astro.) Called Lee and he had no clue what was going on except to say the mass air flow sensor would not prevent the engine from running.

When I got home, I futzed arouund a little with it and still could not get the engine to run. Then I disconnected the MAF and the SOB started right up and ran like a charm. When I plugged in the MAF the engine immediately stalled (3 times in a row.)

GD computers - it used to be a normal person could work on a motor vehicle.

Next stop - new MAF and read out of computer signal.

Any suggestions???

As I stated in the first post that I made, Check the BARO !!! I am glad you finally did but hate that you had to spend all that money before you got there. As Ramrod knows, you can get bad new parts. You may have also gotten a bug or debris on the MAF sensor wire when it was install or your air filter box may not be sealing good and let the hot wire on the MAF get something on it. Just something to check.

Yep , Makes you just wanta ---------- Eat a TIRE !!!!!

Think he used a spare MAF. May have been setting around collecting dust. You think that may damage it?

An the WHEEL goes Round ,, It seems you are hitting all around the problem , My niece has a 2002 CV, an if you take the hose off to the throttle body , OR un- plug the MAF , her car wont start , She called me one day cause her car kept stalling out, at red lite , had a low idle sometimes / sometimes not, AND now get this -- there was a intermitt BUZZ sound going on rite at the air filter box ( like a preturb bee in there ), I pulled off the MAF , gave it a couple shots of electric contact cleaner , Reinstalled , An shes never had another problem with it an thats been a little over 1 1/2 by now . Darnest thing I had ever ran into , As for the Buzzing ?????

Catfish and Ramrod - you were correct on the MAP sensor, but since it had been replaced only 10,000 miles back, we skipped over that at first. Took the 'Chicken" to my friend's son who replaced the Mass Air Flow Sensor and checked the program.

After a couple of local trips, drove it to Watkins Glen last weekend (250 miles one way) for the auto races and it seemed to run fine. Lee had no explanation why the MAF sensor would go bad after only 15, 000 miles, but it only cost me about $225 for the sensor and another $200 prior to that or $425 all together (between the two garages), which included new platinum plugs, transmission flush, coolant flush and injector cleaning, plus the new (rebuilt) sensor.

Thanks for all of your help.

OOPS - I meant to thank Pakus for his comments about the MAF -sorry! No offense intended - none taken hopefully.

Still, thanks to everyone.

When replacing plugs I always recommend a set and the original type. Different type plugs of different materials (even with the same gap) fire in a different heat range - might be enough for computer snafu. If running lean use LOWER octane fuel for less temp and burn. Also keep in mind - carbon clogging the converter can foul stuff up. Where does the exhaust go on a high miles car with converters when the converters are clogged solid and blocking the pipe?