engine miss

[HISSIN50]

hey folks. here goes. i drive the 88 gt stang about once or twice a week. last time i drove it, it ran strong. i started it up and drove it yesterday, and it is missing pretty bad. idles normal - no miss and idle speed the same. as soon as i accelerate, it misses. the miss is consistent through the rpm range. seems to do it only under load (cant get it to miss idling in the garage). i havent tried to work on it yet. i got no codes. search of related topics only seemed to indicate the harmonic balancer could be gone. i would think it would miss in all conditions were that the case (at idle, etc). not so.

i have normal vacuum (gauge in the car). im not sure how i will test the ignition out, as i cant do diagnostics while driving up a hill or accelerating (im crazy, but not that much). i plan to try to check spark at all cylinders, fuel pressure, etc, but since i cant replicate the miss in the shop, i was hoping your experience might produce some ideas on where to look. i was thinking maybe the Hall effect pick up dumped on me, but i dont know how to test it. could a bad coil cause this (im thinking so - coil works but not within specs). just dont get how it ran great one day and like poo a few days later. it feels like im runnin on 5 or 6 cylinders (doesnt even sound like a stang). no pinging, etc. car is stock (still S.D.), timing at 14* (no recent changes). all PM is done (pcv, air filter cleaned, fuel filter, etc). im halfway through a tank of gas, so dont think it is bad gas.

any and all ideas are very welcome and appreciated. thanks guys and gals.

 

[jerry beach]

Hows it going man? If you dont have a FP guage, I would advise you go get one. That is the first thing I would check. Maybe the FPR has gone bad or the FP itself is on the way out. My theory is it gets enough fuel to idle fine, but under load, when demand goes up, it doesnt have sufficient pressure or volume. I have seen this happen. The more you press the gas, the worse it runs, right? I can tell you how to do a volume test if you dont have that info already, I am guessing that you do cause I have posted it several times. Any who, thats what Jerry would do, check FP first cause its easier too. If the prob is electrical in nature, it should have showed up when you scanned for codes. Come to think of it you should see a lean condition on the codes if its fuel related. Try and drive it very gently and see if it does it at a certain rpm or anything. Would be nice if you could hook the FP guage to it where you can see it while driving, I have heard of duct taping them to the windshield. Then you can see if FP falls when you experience the missing. I would try pulling codes again too, if you have driven it since you pulled them. Sometimes they can take a while to set code. Good luck Hissin, and keep us posted.

BTW, things are looking great for us here at the new house. Business is picking up and we are getting our classroom ready for the new year. Hope you guys have a Merry Christmas too. Later.

 

[jrichker]

Miss under load at all engine speeds, both while cold and warm -

1.) Cap, rotor or wires - remove & check for condensation on the inside of the cap (if you can get water to condense in Arizona). With the hood up & lights out, look for an electrical show - sparks jumping around on the wires, etc. Some WD40 is great to displace the moisture. Us an Ohmmeter to check the spark plug wires: they should ohm out at about 2000 ohms per foot of lenght.
2.) Coil
3.) Spark plugs.
4.) Low fuel pressure

 

[HISSIN50]

Jerry and Joe, thank you very much for the responses. i shall do both. i dont have a permanently mounted fuel pressure gauge (been meaning to do that), but i do have a testing gauge. ill give it a shot, as well as checkin the coil, wires, cap, rotor and so on (i dont think water condenses here. LOL.).

normally im not so retarded as to post something like this without checkin it out first, but its been nuts lately (g/f's car got ripped off, so ive been playing taxi driver, and kinda wanted to keep the stang viable). typical.

jerry, glad to hear all is well on your end. sounds like you are gonna have a nice holiday season. im gonna try to come back in here more once things settle down (if/when).

thank you both very much.

 

[HISSIN50]

ok, got more info for the experts. fuel pressure is 40 psi with engine off and key on. with engine running at idle, its at 32 psi with vac line on, 42 with line off. i have never checked it before, so i dont know what is a normal trend. with engine idling, vac line on, the pressure goes up to 34 psi with with a rap of the throttle. if i keep it at a constant speed (i.e., 2000 rpm), as i roll the throttle, the pressure goes up a couple psi, then goes back to 32 once i stop rolling the throttle same trend as the vac does). how do these numbers sound (i think spec says ~30- 45 is good). reminder: stock 88 gt, stock F.P.R., etc.

coil and plug wires ohm out good. pulled cap and the cap and rotor look good (only about 500 miles old). i got no light show, performing Joe's plug wire test. i put the test light on every wire and i had nice consistent timing light pulses. the wires are mallory 8MM and look fairly new (though i know they have not too long a life- few years).

the strange thing is that my timing has changed. i set it at 14* a few months ago. now it was at 10*. i am real anal about triple checking my setting when doing timing, and the hold down was reefed down. the rubber on the balancer looks good (am i lookin at the correct rubber? the o-ring type seal on the face of the balancer). i have now marked the balancer on either side of the rubber o ring, so i can try to tell if it slips. the balancer does wobble a little. it has done this since i got it. i didnt worry since it ran fine and the o-ring was intact (most people mention that the o-ring being messed up and or vibration is/are the tell tale sign that replacement is required).
i am concerned that this may causing some/all fault. at most, it slipped a few degrees.

i checked codes. KOEO- code 11 (good to go)
KOER-code 94: thermactor stuff and or transaxle switch. i have no idea what the former is and if it could cause my symptoms (is it air pump and other emissions?). this could have been present for awhile, as i have not ran codes in forever.

jerry, in regards to your request: when i drive it (fully warmed up -165-170* is as hot as it gets since it is cold in tucson). taking off, as i engage the clutch in first, i can feel the the miss. needs more gas/clutch slippage to keep from lugging. i am babying it, so i shift at low rpms. when i engage the clutch after shifting into 2nd gear, i am turning 1500. it lugs/chugs and i think i hear faint pinging, even with feathering the throttle. it misses all the way through the rpm range, though it obviously runs stronger at higher rpms. it has a strange cadence; almost sounds like a harley A/C'd V twin. as i drive along, i hear "da da da da da da. like a good miss.

can a bad balancer cause symptoms like i have (like a miss). the motor sounds fairly smooth at idle, though there is more vibration than before. as i rev it in the garage, it revs fairly smooth, but upon letting off the throttle, it misses a time or two as it comes down from about 1800 to idle.

does any of this make sense to anyone? i dont know where to go next, nor do i want to toss money at parts until i find the right one. i would really like to pinpoint it. please share experiences and or more tests to try. let me know what you would like me to do to provide the necessary info.

thank you very much. i really need and appreciate all help.

 

[Michael Yount]

Fuel pressure looks fine to the extent you can check things in the driveway. What's happening when you drive it (FP) remains a mystery. I don't think I can add much to what's already been suggested by the others. If it really is 'missing', then some cylinder(s) are not getting either fuel or fire. Given the sudden nature of the problem -- your comments about the coil's performance have me intrigued. I believe were it me I'd pursue that a bit further. No one wants to throw parts at a problem - one way I like to think about that is where there's a suspect part that at some point I'd like to upgrade anyhow, now's a good time to do it. So, what hotter coil did you want? I'd also check out the electrical system - grounds clean? Battery ok? Alternator charging properly? I've seen incredibly quirky engine problems show up when a battery was on it's way out. Don't ask me how - like so much with electrical systems, sometimes it doesn't seem to make much sense. I don't think I'd worry about the balancer -- assuming it's truly a miss. A bad balancer can cause vibration, but it won't make an otherwise well functioning engine develop a miss from one drive to the next. Remember, the computer shifts the timing around quite a bit, so if the timing changed - perhaps the module/computer is doing something funky that's contributing to the mystery. Sorry I couldn't be more helpful.

 

[jerry beach]

My 88 developed a sudden but steady miss once. The shifter shook like crazy when trying to accelerate. I have read there was a prob with the fuel injectors in 88. Thats what was wrong with mine. I limped mine back home and pulled the wire off the dist. cap one at the time and isolated it to a cylinder. Lucky for me I was able to reach that inj. and pulling it made no difference in the idle either. It still idled fairly smooth as you describe and was not very noticible revving in nuetral, but very prominent trying to drive the car. My injectors were also damp around the weep hole. I replaced all of them with ford racing 19#. This was at 100,000mi. Something you can check anyway. Good luck man.

 

[HISSIN50]

Michael and Jerry, thank you both for the responses (again). i was leaning towards the balancer after i typed that last night (spent some time reading up on old threads). the fact that people say it's bad if it wobbles....and mine does a little... but if it only causes vibration issues, i may pass (seems like, when goin bad, they start out as a vibe at a given rpm or two, and in worsening conditions, causes rumble at all rpms.) seem accurate? (this is based on balancer threads).

the electrical seems to be fine (in AZ, corrosion is not really an issue). i had the same thoughts about the battery (it only gets started a time or two a week, and runs a stock gerbil in the wheel). tossed charger on and it was pulling only 2 amps. starts no problem. but interesting since it has just gotten cold and rainy here.

im gonna pull wires to pinpoint bad slugs. i tried a balance test (never done it before). when i held the throttle down for a few seconds at the beginning of the test, the puter held the rpm constant at that rpm when i let off. all i got was flash-flash, pause, flash-flash. i assume that is code 22 or two repeated. it was not consistent with what i expected (single code of 1-8, perhaps being repeated). the injectors were replaced about 30K ago by previous owner.

i am now thinking that i should start with wires(dont trust my VOM. some wires showed too low a reading. think VOM is a POS), then coil, then fuel injectors? (not necessarily replace the latter, just check them better -im too lazy to pull the upper at this point. i dont want to introduce more variables).

Michael, you are right about the stuff with replacing things that were wanting to be upgraded. im totally this way, and justify a lot purchases with this and the "good PM saves future tows, etc." i was just trying not to do it now. holidays and forkin out cash for a car last week kinda killed me.
so i may lay out some cash and see what gives. were it an injector problem, would i not get a code?

and i may do the balancer, as the wobbling is disconcerting. i found a CAT damper that is good to 12.5K and complies with SFI 18.1 specs. costs 60 bucks new. it may not be a cure, but it will solve a future problem. mine may be orig at 156K.
i just woke up, so i hope this makes sense..
thank you all for the all the help. i will let you know what i find.
ps, michael, i was thinking of getting a msd coil, as i can get one locally. i would get a crane coil if they were available, as, if i ever did an ignition upgrade, it would be to a crane, i think. any thoughts?

 

[Michael Yount]

I guess it's difficult for you to distinguish between a vibration and a miss - and I realize a miss often causes vibration. Again, if you're sure it's missing, I don't think the damper has anything to do with it. One thing you might try with the injectors, is one by one, disconnect their electrical plug - drive the car. If you unplug one, and it doesn't run any different, something's probably up with that injector. Same test can be run with plugs.

Don't know much about coils. My brother put a Ford Racing coil on mine when he had it. THat, and MSD cap and rotor, and fresh wires/plugs are all that's been done to mine.

Is there anything that might have bent one of the pickups (not the pickup, but the things that swing by the pickup) in the distributor? My brother had a problem with mine when he had it - it just seemed to run out of steam around 4000 - it would rev, not miss, just with no authority. Mechanic found a couple of the 8 things that swing by the pickup in the dist. were bent. He straightened them and it made a bunch of difference. Wild hair.

 

[HISSIN50]

Michael, good stuff. you and jerry both hit it (and it is something i recommend all the time, but neglected to do myself). i pulled each plug wire and found that number two made no difference (the balance test must have been trying to tell me that [see above post of mine ref code. 2,2]). i stuck an extra plug into the wire and ground it, and i have a ton of spark. so i deduce that the injector is dead (you both hit that one).

now how do i go about determining if it is an electrical problem or the injector itself? is a noid light the best way to go (Mike, you have the C.S.S. disorder; i have that and C.H.S.). i think i hear faint clicking in that injector and the one in front of it (used for comparison). done with a screwdriver (too lazy to use stethoscope). the motor and mechanical fan are so loud, though....... i dont own a noid light (they are cheap i know), but is that the best way to check the injector for juice? i was afraid to try like a test light or something as i dont know how much juice the injector wires transfer (dont want to overdraw with the test light). ideas?

Michael, as an aside, you are right about the miss vs vibration thing. i have never had a car with a balancer, as such. the problem is that the car never is real smooth; the idle is gruff, which i like the sound of. there are always some vibes, so i cant distinguish if the additional vibes result from a miss or if the vibes can be so bad that it feels like a miss. the tell tale is driving and hearing the miss upon acceleration, etc, i suppose. if i ever sit in a car with a bad balancer, i will know. when im in doubt, i just try to give as much descriptive info in nauseatingly long threads, so that everyone can make their own interpretations rather than my biasing things with perhaps incorrect assumptions (miss vs vibes). and i could not figure out how the base timing (spout pulled) could change unless the damper had moved (spout takes the puter out of the loop, no?). i thought that would be a totally mechanical timing reading. anyhow, like i said, i just try to give info and what i think, and let you (the experts) tell me how it is. cool?

please let me know about further testing on the injector. i found nothing in haynes. i will check "veryuseful" in a few (just thought of that). thanks to all again.

 

[Michael Yount]

I think it takes some specialized equipment to test injectors properly. You have to be able to energize them, check spray pattern, and measure volume/time. Not a clue how to do that myself. Can you put a stethoscope on one that's working and see what sound it makes, then switch the plug on the bad one to a good one and crank it up. Put your stethoscope on it - if it's still energizing (even though the timing will be incorrect for the engine) then the wiring/plug is ok and it's the injector. If it's not energizing, then it's the wiring plug. Would that work? Assuming one plug will reach another injector - you might have to jumper it.

 

[retro50]

You might want to test the cylinder pressure in the #2 cylinder. That is if you check out the injector first and it is ok. You need fuel,spark,air + compression to fire the cylinder. If everything checks out fine and you still have a miss. Just take a compression test. You could have low or no cylinder pressure.As far as your timing is concerned your timing chain can stretch and that will throw off the ignition timing as well as valve timing. But usually it is only a couple of degrees.

 

[rdksek844]

If all else fails, check your pickup in your distributor. I had a buddy that had the same exact problem and it was his pickup.

 

[jrichker]

Simple fuel injector test (if you have an old injector handy). This will test the electrical side of the injector.

First remove the coil wire from the distributor and ground it. Then take an old injector and connect a piece of 3/8” air hose with a male quick coupler fitting on it to the injector top. Connect the injector to the compressed air supply and to the injector wiring. Get a plastic cup of very soapy water and immerse the injector tip in it. Apply about 40 PSI air pressure to the injector and crank the car. When the injector fires, it will make the water bubble.

This also works to test injectors currently in use, but requires a little more effort to remove them for testing.

 

[jerry beach]

That figures, #2 injector decided to quit on mine too. As Mike said switch the injector wires with #1 inj. Then do you plug wire pulling routine and see if the prob migrated to the #1 cylinder. That will tell for sure if its the injector. If your engine idles rough, there may be another problem. But who knows, you put 8 new injectors in it and it may idle perfectly. I would go ahead and do a compression test on that motor if you havent recently. It should be OK, but I would want to know for sure before throwing $ at it and hoping it runs right. I know a guy with an 89 stang with 190,000mi and it is still running good.

 

[Mustang Ricky]

did you examine the sparkplug. i had a miss once. it turns out the plug had a hairline crack causing it to arc.