This is really pissing me off..

Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

Could be the timing chain. Or is it a gear in the mustang? One of them had a similar problem with another ford.

It runs normal for 2 minutes, then this symptom comes out of nowhere and doesn't go away until it warms up or you go WOT? The 2 minutes part is throwing me off, but I'd still say yo have a rich condition air/fuel problem. It would make sense, since the computer is set to run rich until the o2's warm up anyway (which is why you should let your car warm up a bit from a cold start before jetting down the road) and if anything isn't right, like a dirty MAF sensor, aging o2's, etc it will only exacerbate the drivability problems associated with driving cold. (next time it's cold out, have somebody tie you to the hood naked and go blasting down the road and see how you like it... your engine is just as uncomfortable) I'd start with a tune up, but it sounds like the cheapest way out is to let it warm up first. If you aren't having any luck pulling codes, than I'd bet you'll find something interesting if you start pulling spark plugs.

Like Richker says - pull the codes - they'll help show you what is wrong. Sounds like something is happening when it goes from open loop to closed loop operation - which may be O2 sensor issues; but the codes will tell you.

ive tried multiple times to pull the codes on my car using jrichker's technique with a jumper wire and nothing happens. i dont know if thats because i dont have any codes to pull...or if my check engine light bulb is out...i dont even know where the check engine light is on my car. ive never seen it come on...even when the car is running like crap. i dont know

Mustang5L5 said:

I get detonation at the end of the long 3rd gear pull at the track with 10 degrees and 87 octane. I have a 190lph fuel pump waiting to go in for that problem, but not sure if the two are related. The rough problem only started 3 months ago. The lean problem has been going on for a while.

Click to expand...

87 octane? That's stang abuse. My car will not even run on it, I've tried it several times at different gas stations to no avail. Runs like a raped ape on 93 though... you must be nuts. I could see daily driving with it if it will (mine won't) but taking it to the track with 87 and beating on it? You deserve whatever happens.

did any of you guys every change your fuel filter

stangbear - mine runs on 87 just fine, toodling around or pushing it. With only 9:1 compression and reasonable ignition timing, there's no benefit on mine to running higher octane. In fact, it seems to get about 1 mpg better fuel mileage not doubt because the 87 ignites more easily and burns a bit quicker. In the 2 years/12K miles the motors been together, I've never heard it detonate once. But if yours detonates on 87, you have no choice but to cut timing back or increase octane.

Stang bear you seem like a cool guy, but that was just a real stupid post. but its ok, I make more than my fair share lol.

My timing is cut back, I'm not running any advance at all and I absolutely refuse to retard it. My '79 wouldn't run on it, My '84 wouldn't run on it, my wife's '89 doesn't run well on it, and my '91 absolutely won't have anything to do with it. Could have something to do with the high miles, but my wife's engine is brand new. It'll run on it, but it gets even worse mileage then with good stuff and doesn't run as well. Any moderately stock 5.0 can be tuned to run fine on either, but it will never run as well with 87 as with 93, nomatter how well you dial it in for the octane you intend to use- and my Dad's '01 (which runs fine on 87) goes through two filters to my 1. I'd rather have it tuned to run on good stuff and pay another $1.00 a tank for better performance; not to mention not having as much crap getting sucked into my engine. This may vary from coast to coast, but I'd rather be safe than sorry. If you are so upset about the price of gas that this matters to you, you shouldn't be driving a Mustang anyway.

rolliin, if not mentioned, check the values of the lambdas and ECT (ACT too, if you want). they may be reading within spec (no code), but be incorrect for the situation (i.e. the ECT is telling the puter the motor is warmer than it is, so the puter leans out. the reading is within range, but not correct for the situation [if your motor is cold]). basically, it is out of calibration.
the lambdas are not used under WOT, too (if that helps in your diagnostics).

just some things to check, if you want. good luck.

PS, im not touching the fuel octane stuff. LOL.

"but it will never run as well with 87 as with 93, nomatter how well you dial it in for the octane you intend to use- "

I don't think your statement can be broadly applied to others' cars Stangbear. These cars have low enough compression to run easily on 87 octane - at least when new; as someone else said, that's what they were designed for. You're correct - that situation changes with miles (how many on yours anyway? Iron heads or aluminum?). Unless you've advanced the timing to the point that detonation on 87 is a problem, if your car is working properly, there is no performance advantage to running 93 over 87 in a 9:1 motor. In fact, I'd argue - all things equal - that the 87 may actually work a bit better because it's easier to ignite and burns a bit more quickly. In fact (he said scratching his head) - Car & Driver actually did a test a while back on this very issue - they confirmed that there was no performance benefit to running a higher octane than the car was designed for. Unless of course, the higher octane allowed for more boost or more timing to be added. They had a couple of boosted cars in the test, and some with knock sensors. They benefitted from the higher octane because the computer allowed more boost/timing with the higher octane fuel. My wife's Bimmer is 10.3:1 compression - they request that you run 93. You can run it on 87, but it has knock sensors with will retard the timing to deal with any detonation that might occur in that scenario.

If the engine's halfway fresh, and all systems are go, 9:1 ought to run the same on 87 as it does on 93 - you just save some money. All bets are off as the miles pile up - carbon deposits build up, detonation is more of an issue with less timing in those circumstances. No two engines are the same - so us comparing our car to another in this regard is a waste of time. One may require higher octane to keep it from detonating and another may not. Other factors that impact it are ambient temps (Phoenix might be a bit different than upstate NY in June), and different blends of fuel that are used in different parts of the country.

As for calling it "the good stuff" - there is nothing cleaner or 'gooder' about 93 than 87. They all run out of the same refineries, same transport trucks, same pumps, same filters, same quality control process. The higher octane fuel is simply more difficult to ignite because of a different blend of hydrocarbons/additives, and consequently it resists detonation better than lower octane fuel.

So, 5L5 if yours runs fine on 87 (as mine does) it's not Stang abuse. And Stangbear, if yours won't run on it - then it won't. Simple as that. But it doesn't mean that others' won't or that they're somehow mistreating their vehicle. That's right up there with the Amsoil vs. Mobil 1 vs. dino oil debate in my mind.

Happy holiday guys! Who's gonna win in Indy/Charlotte?

ECU - the check engine light doesn't come on for all codes; so if it's functioning correctly, it's possible that there are codes even if there's no check engine light. WalMart sells a scanner for about $20 - don't know if it will be anymore effective than JRichker's method though. Can't help but think of MacGyver everytime I hear about pulling the codes with a paper clip (and a banana peel!). I just think it's cool that that can be done.

Mr. Yount


To avoid hijacking this thread (something I'm talented at ) lets just say I agree with you for the most part, and leave it at that. To answer your Q's: factory iron heads, and I'll turn over 234,000 miles this week. And I'd rank it more with the Ford vs. Chevy debate than the Amsoil vs. Mobile one. I just know that when I was at the shop, we noticed a difference in almost every V8 car we recommended higher octane to, in mileage, knocking, and how often they needed a full tune up- as well as how messy the tune up parts got in the meantime. Newer cars are nowhere near as prone to problems, but for the Fox's (especially the carbed ones), and the applicable variants of F-bodies it was night and day. Back to the topic, kinda... if I had a stang and everything checked out but I got a pinging out of it on a long third gear pull, the first thing I'd do is stop putting lawn mower gas in the tank

"the first thing I'd do is stop putting lawn mower gas in the tank...."

C'mon - peel those last 2 fingers back, you can let go of it if you try!

At the risk of sounding even more dense than usual... I'm sure that was a joke, and I bet it's funny... I'm just not getting it. ( In my defense, it is way past my bedtime )

this exact thing happened to me, it turned out to be my fuel pump..