she randomly wants to be lazy...

[Axel Kain]

87 GT 5.0 HO, 5 speed, MAF converted - after about 2-5 min of driving it will start to backfire through the intake, buck, and stumble. If I floor it, she fires off, and goes well. once it's warmed up a bit (with barely any indication above 130 on temp.) it will be ok, unless I am going up a hill/ heavier load in 5th, then it lacks power and stumbles and pops again. once on a level plane again its ok. messed with timing, spout out! - 10, ok, 14 is better, but still does it. I am currently running low oct. gas, and have pulled timing back to 11, or 12. TPS appears to be operating properly and within range. - set to .862 (yes I have a fluke.)

codes - 82, and 85. canister is out. not noticing any vacuum leaks. it does hunt for idle within 150rpms or so of 1000. the passenger side of the firewall where all the solenoids and vacuum mess is seems a bit garbled by PO, but from what I can see it looks to all be sealed.

it runs great, and goes well when it is not doing this condition, be it cruising or running through the gears! its almost like a switch the way it comes and goes.

when trying to accelerate normally while its acting up - it sounds and feels like I can feel every piston hit, and you can hear distinct deep da-da-da-da-da-da-da of an exhaust note as it slowly accelerates, instead of the smooth bwaaaaaaaaa.......

only running catless X pipe, MAF conversion, and smog delete.

 

[MustangLX-5.0]

You check your plugs and wires? Make sure you don't have a bad plug or wire.. that will cause similar issues. I am also thinking you may have a problem with the MAF sensor. How does it idle when its cold... when you first start it up? If its a used MAF sensor, try running some MAF cleaner over it. No guarentees there but worth a shot. Canister is out? Is the vac line plugged? This would indicate code 85. Code 82 is probably from deleting the smog pump.

Other ideas here?

 

[HISSIN50]

Going up hills in 5th? What kind of RPM are you at?

 

[Axel Kain]

plugs and wires are new from when I installed the engine (rebuilt) about 3k miles ago. MSD cap, rotor and wires. I think the plugs are autolite's.

canister was removed prior to my having the car, not sure about vacuum hose location/route.

when I first start up it goes to ~1500, then will come down and stay around 1000.

5th, anywhere between 1200-1800RPM.

I notice that when its acting up within 20-80% throttle range if I floor it, it clears out, and runs fine for a few seconds within that range, then goes back to being crappy.

how much of an affect like this would a bad temp sensor have on this? I would have said, oh its o2's since it does it once warm, but it would click out of the messy running, and go great after that which kinda drops that thought. its not fan wash, not consistent problems. fuel pump is brand new.

 

[MustangLX-5.0]

1200 - 1800 RPM... how steep of a hill? 1000 RPM at idle, that's a bit high. Run the engine till its fully warmed up, then disconnect the IAC and adjust the idle till it sits around 725 - 775 RPM. If it wont go down and more, then you have a vac leak someplace. The canister vac hose is typically connected to the very front of the upper intake plenum. It comes out on the front, runs down a little and then behind and below the alternator then comes out just to the left of where your smog pump used to be. The canister was located directly below your air filter box. If there is no visble vac line, check under the front of the intake plenum. If there is no line there, then there should at least be some kind of plug on it.

Does the exhaust ever burn your eyes or smell like its running rich?

 

[fivespeedsteed]

the temp reading is wrong, im telling you kevin its the coolant temp sensor. replace that and the temp gauge goes right to the middle.

not saying i know thats your problem im just saying the 130 degree figure is wrong.

i found this out after being on here but anything blow 1600 rpm is boggin down the 5.0 wind out 4th more.

 

[Axel Kain]

suposedly there is a temp sensor for the gauge, and one for the computer, seperately.

Im not seeing any vacuum hoses on the front of the intake at all, there are a couple large hoses, one goes from one port to another on the upper intake, and one that goes striaght towards the front of the car but is blocked off.

when decelerating I normally get popping in the exhaust, when it's in it's stupid mode, that popping sounds different than normal too.


the big issue is crusing and first starting off, it will pop through the intake, if I smash the gas to the floor, then come off to where I want it to be, it drives fine for like 5 seconds.

 

[HISSIN50]

suposedly there is a temp sensor for the gauge, and one for the computer, seperately.

Correct.

Im not seeing any vacuum hoses on the front of the intake at all, there are a couple large hoses, one goes from one port to another on the upper intake, and one that goes striaght towards the front of the car but is blocked off.

The one going straight forward (that's capped off) probably went to the purge solenoid.

 

[Axel Kain]

I noticed today when I was leaving work, started up, and let it idle. just sitting there I knew when it went into and out of its condition. the idle got more distinct and choppy, keeping about the same rpm until it kicked out, and it rose ~50 or 100 rpm, still staying around 1000. I may need to time it next time it does it. but just sitting there idling, then I hear it change, run goofy for a min. or 2, then smooth out, and be done with the bad crap.

when I got home I had it idling, disconnected the IAC, it dropped directly between 500 and 1000 rpm, and held steady. plugged it back in, and rose to ~1000.


also, I never notice this thing to be running rich, even when in a shop...while the guy with the 47 chevy pickup with a 350 in it and open headers stinks the place up in about 2 min!

 

[Axel Kain]

well, installed 2 new o2's as I had found a thread mentioning a similar issue. 1st run its doing better already it seems. tomorrow will tell me if they where the issue or not. although, I now can rumble around 20-30mph in 3rd or 4th and be able to hit the gas and go forward smoothly. as well as no crap while driving and warming up.

although, even with a new temp sender, no real movement on the gauge, I feel there's an air pocket or 2, any tips for system bleeding?

 

[xtreme02stang]

I've heard of people jacking the front end of the car up to let the air bubbles escape, could try that.

 

[Axel Kain]

would it be enough to burp from a loosened throttle body coolant hose?

 

[HISSIN50]

You can purchase a radiator funnel from the parts store.

You really need to let it idle with the rad cap removed to get the air out. Be careful of hot coolant splashing out of the open radiator (this is where the radiator funnel can be of assistance).

 

[SVT32VDOHC]

3,000 miles is a lot of miles on plugs for a freshly built motor that might have had bugs or other problems. I had a backfiring and sputtering on a 5.0L and the plug gap was worn to .072. I put new ones in at .048 and the car never ran as good as it did the day it got plugs. The thing was perfect.

 

[Axel Kain]

well I checked the coolant hoses, and outlets. it isnt getting much more than 140-150 degrees. got a stuck open T-stat. so I'll be getting that fixed next.

still not doing near what it used to, still get a random pop sometimes but it isnt bucking and jerking and sputtering all the time!

probably will look at the plugs, make sure they aren't burned up or fouled.

 

[Axel Kain]

did the thermostat (195 degree)...BIG difference in feeling and....heat in the car! haha. I think that and the o2's where what was really screwing with it. rechecked timing tonight, right on 10! (spout out)

I think when my uncle installed the t-stat, maybe he had it backwards, or something happened to it, as the copper sliding cylinder was wedged into the supporting ring/tabs. so it opened, and....stayed open!

still going to check plugs, considering its now pretty well broken in!

 

[Axel Kain]

You can purchase a radiator funnel from the parts store.

You really need to let it idle with the rad cap removed to get the air out. Be careful of hot coolant splashing out of the open radiator (this is where the radiator funnel can be of assistance).

shoulda had this in the previous post...I have one of these at work, includes the 45 degree bend too! this thing has been a lifesaver!

also - once the system got hot enough and opened up....woosh, it bled beautifully!

 

[Axel Kain]

one more bit - found I had a leaking heater core, bad enough to the point that it was 3/4 empty when I replaced it after sitting all night. pull the hoses off, no mess, pull it out, no mess, flip it upside down...little bit comes out!

I seriously feel this had a BAD effect on how well the ETC sensor was reading, since it had basicly no coolant in the pipes initially!


still need to check/maybe change the plugs!