will not having o2 sensors in place cause an 88 5.0 bird to sputter and no longer accelerate at 4000 rpms? i have talked to several people who said no, but i have replaced every sensor on the engine since i have had it (except for bunging my exhaust for o2's) and nothing helped. it acts like it hits a rev limiter or something.
also will no o2's cause poor economy?
Missing O2's will certainly cause poor economy, but if it's a stock non-HO 5.0 you're not gonna get any more than 4k RPM out of it anyway. They simply can't breathe at that RPM.
Now, if your sputtering and refusal to accellerate at 4K RPM happens at around 110 MPH, that would be the speed limiter kicking in.
Isn't your 4K prob, O2 sensors are ignored by the computer at WOT...
it happens in every gear and trust me, it will run WELL over 110 :D
it has an HO intake, CAI, mustang headers, gutted cats, and no ler. should be able to breath.
what could be causing this? the car pulls hard up to 4k, then its like it hits a rev limiter......
forgot that it also has a 65mm throttle body.
scanned it at autozone today and the only codes it was throwing were TPS out of range and something about the IAT. i put 3 different IAT sensors in it and none helped the way it does. going to get a digital multimeter soon so i can set the TPS
what cam and heads have you?
those affect breathing too ;)
Also, what eec do you have?
If you have the stock cam, your not going anywhere. You probably can't even hit the rev limiter with the shiznitty stock truck cam shaft in there.
That tps might be confusing the ecc into thinking it hit redline. I had a similar prob. but it would break up and not go between 3-4 grand. I changed the ignition switch and hooked my vss signal wires up and it went away. not sure what fixed it, also mine would only do it sometimes.
To add to this: If you've still got the stock cam AND the stock E6 heads you're not going anywhere. The stock cam and E6 heads are what makes a non-HO
not HO. All the exhaust and intake in the world is not going to help you. With all that you might, just might, under ideal conditions, eke another 10-15 horses out of the engine, but it'll be at an RPM you can't use (because the heads and cam won't allow the engine to spin that fast) and you'll lose an equal amount of torque down low (for example, Ford gained 5 horses when they added dual exhaust in 1988, but lost 5 lb-ft of torque).
You might be experiencing valve float as well. The weak-ass stock valve springs may not be capable of pulling the valves closed fast enough at that RPM. When brand new they'd have been hard pressed to do it. 20+ years old they're lucky to pull the valves closed at
idle. There's a reason the non-HO engine had a 4500 RPM redline.
..and unless you've done something to disable the speed limiter in the 1988 EEC-IV ECM (such as replacing it with an '87 or cutting the VSS signal to it, which would remove the limiter but cause other drivability problems) you're certainly
NOT going faster than 110.
Could it be as simple as the stock fuel pump cannot keep up anymore, and it's running out of fuel? :hick:
Could be a possibility, but usually a weak pump will show at different RPMs, depending on gear but always at WOT... Probably wouldn't hurt to install a fuel pressure gage and see where pressure is at 4K...
You could install a 6cyl tach, it will read 6K, problem solved... :hick:
If you're feeling really frisky, get a 4cyl tach and spin it up to 8G...If it's the "brick wall feeling" you described, then it's probably either hitting the speed limiter or you have a valve float issue... I doubt it's valve float, I've seen some sorry springs in my time, but never seen a SB Ford that wouldn't rev at least near 5K... SO heads ain't great at RPMs, but it should rev more than 4K, my '86 Stang with E6 heads would pull hard to about 5300, then run in to the wall you described... Didn't have a speed limiter so had to be the springs...
Sooo this leaves speed limiter but if it does it in any gear, puts us back at fuel pump, valve springs or maybe a iginition problem...
get some heads of a 91-93 bird or cougar. could probably use the cam too. There alot easier to find if your in mustang territory.
The tbird I have right not won't even rev to 4k. I can just sit there and hold down the gas and it stops about 3800.
You can get the stock speedo to read over 110....:mullet::burnout:
it has new plugs, plug wires, cap, rotor, module, and the distributor shaft feels like new so i doubt it's ignition related.
i'm still on stock cam and heads, but the car has turned 6500rpm's when my brother had it.
we have a fuel pressure guage and it has good fuel pressure.
as for the 110mph limit, i made it 25 miles in 12 minutes, 2 miles of that was stop and go and about 4 miles was at 45mph. averages out to 125mph if my math is good....
Well I'm calling BULL shiznit on this... Six miles of stop/go & 45 mph averaged into 19 miles would probably mean you'd have to be running 150-160mph the for the 19mi... AS I SAID, BULL shiznit...
As far as prev turning 6500 another BS, the computer limits RPMs to 6250... Ain't happinin' with STOCK ford valve springs anyway...
Wanna try another story???
Like Tom said, I'm doubting it's the springs as well -- at 4K RPM anyway...
Anyone know if there's a difference between the springs from HO to non HO? Part #'s or anything like that?
Also remember that a
BONE STOCK AOD WILL NOT GIVE 4th/OD @ WOT.... (http://smiliesftw.com/x/yuck.gif)
Gotta back off it a bit.
I'm`curious what tach you have as well. The E7 that mustangs have are the exact same as e6 minus the "high swirl" parts. If you factor in the cam, you have a turd. I have gotten my car over 4000 rpm in the past. It has no power. From about 1 to 2.5k rpm, the car feels decently fast, everything after that, I had to let up to let it shift.
I have had a couple of these cars faster then I will admit, but I went 13 miles in 7 minutes. About 7 minutes anyways. I used to live 13 miles away and moved when I turned 17. My dad would call me at 11pm and ask why I wasn't home, So I'd tell him I was on my way and get back less then 10 minutes later. I knew the road very well. It had a 60mph speed limit, and is dead as anything after about 5 pm. It uses for gravel trucks and thats pretty much it. I quit speeding after I got pulled over. I actually didn't know I got pulled over...
I got home and turned on the tv and started watching cops. Went and started a $1 pizza in the oven, and heard a knock on the door. There was a Utah highway patrol officer there. I asked him if there was something I could help him with and he said come outside. I did. He asked who drove the black car. I said I did. He asked me how fast I was going and I tried to play stupid and pretend I wasn't driving. He told me that he didn't clock me, but flipped around and did 110mph trying to catch up to me and couldn't. I told him my speedo only read to 85. He laughed and said the old 5.0 were alot better then the new 4.6's. He said if he ever saw me again I would get pulled over. Never saw him again.
I dunno about part numbers, but Mitchell ONDemand has different specs for HO VS non HO springs, so I'm guessing they're different parts. I've posted the spec table below.
I know my stock non-HO engine (only mods that would affect power are removed silencer and off-road style [no cats] true dual exhaust) falls on its face at about 3500 RPM, and that's with the T5 standard tranny. It pulls like a freight train to 3500, but trying to rev past that is futile, it's time to grab for another gear. It doesn't "hit the wall", so to speak, but it definitely stops making power. Given that the power peak of the non-HO engine was 3200 RPM, and my true duals and removed silencer might bump the peak up a few hundred RPM, that seems quite normal to me.
no "story" my friend. maybe something is messed up in my computer or my VSS, the speedomter is wrong.
i was turning 4k in OD which is .67:1, right? i have 2.73 rear gears, and 215/60-15 tires which measure out to 25.25" tall. if you do the math, it comes out to roughly 160mph. it took a long time to get to 4k, but it was there, in OD.
what reason do i have to lie? i'm not trying to impress anyone, it's likely that i will never meet anyone from this site. believe me or not, it's the truth.
anyways, thats beside the point. i need to figure out whats wrong with it causeing it to not rev over 4k
O/D is not engaged at more than approx 80% throttle... It ain't run 160mph even if you had a tail wind...
maybe trans was slipping and it was revving higher than it should have been at the speed it was going? i do know that i was passing cars like they were tied to stumps.
are 88 mustangs also limited to 110?
Your tire diameter is way off...a 225/60R15 measures out to a hair under 24.5" when mounted and on the car...do NOT use tire manufacturer specs for diameter, 9.9 out of 10 times, they're fubar.
I had a similar problem with my old HO equipped 'Bird...at approximately 4k rpm it would stop accelerating...in any gear...like it was the 6250rpm fuel shut off...full tune-up, still did it...new coil, still did it...MSD coil and wires, went away, but felt like it lacked a little power...I believe it was a high rpm lean miss...the reason I think that is because a few weeks later my stock fuel pump went, when I pulled it, the strainer was laying in the bottom of the tank....I think my pump was just on it's way out and the higher output of the coil was just a temporary band-aid of the actual problem.
But a SO 5.0 has no balls @4k rpm... I have swapped to a T-5, mustang shorty headers 2.5" OR-H, glass packs, HO upper and TB and bumped timing....1st gear...max is 4200 and that's pushing it...2nd gear is done by 4000 and all gears after that need to be yanked before 4000.
i'm going to check the fuel pressure again tomorrow. should it remain steady or should it drop/rise?
Idle/cruse is usually around 30-32psi... At WOT F/P should rise to 39psi and hold... If it never makes 39psi, either the pump is foobar or the regulator is faulty...
If pressure rises, then starts to fall as the RPMs climb, you have a weak pump or a restriction on the pressure line...
Mustangs did not have a speed limiter...
if i'm not mistaken, i believe it has 39 psi at idle....
i've had a few people tell me to check the pressure line for kinks. i will be putting it up on the lift today or tomorrow to check.
didnt get a chance to check fuel pressure today. anyone else care to give me ideas so that i can check more than one thing when i check stuff?
no kinked fuel line, but it did run out of gas in my girlfriends driveway. didnt get to make it to the shop.
bad thing about all this is that i am a mechanic and have pretty much any tool i could ever need at my brothers shop.
Mine won't even do 160 :hick: I think a stock Turbo Coupe maxed out at around 145 or so. Being that these cars are 20+years old do you really want to do 160 mph on the stock suspension......
checked fuel pressure. roughly 32 at idle and 40 from just off idle all the way till it stutters. holds 40 and doesn't drop
Is this under a load or in park? Under a load @ WOT will use more gas than in park...
true, didn't think about that. will have to check it again going down the road.
turned 4200rpm in drive today.
anyone want to do the math? 1:1 drive ratio with 2.73 rear and 215/60-15's
Right around 110mph, in a fox t-bird/cougar, it feels a hell of a lot faster than it actually is.....in order to go 160 with that car, you'd have to turn just a little over 6,000rpm...that's not happening.
Gotta remember your converter will be slipping at wide open throttle, too, (it won't lockb up at WOT) so you're not quite at 1:1
True but on a AOD 3rd & O/D are driven from the inner shaft that's splined into the front hub of the converter... Ford says something about it being 60% lockup in 3rd and full in O/D... All I know is there is almost no increase in rpm from converter flash when you hammer it in 3rd...
Still the only way that car is going to run 160, is maybe off a cliff(a tall one)...
i never claimed 160 that i recall
although my brothers 88 stang WILL run 160
In a round about way, you surely did...
all i know is when i left and when i arrived. i left my friends house and made it to Advance Auto in 12 minutes. i left at 7:35 and arrived at 7:47. yahoo maps says it's a 23 miles, so it's not quite as far as i thought and maybe there was a little less of the 45mph section. i was without a doubt turning 4000rpms in OD until i lost OD about a mile from Advance Auto.
anyways, back to the subject at hand, i found out that it started doing this when the previous owner installed an HO upper, TB/spacer, mustang headers, and 19# injectors.
i have ruled out vacuum leaks, so i think it has to be the injectors. will 19# injectors cause this?
i'm about to finish out my HO conversion, have a friend giving me a SD HO computer, just gota get a cam and heads. i have heard that the heads don't make much of a difference, is this true? i would rather just get it running good for now because i'm buying an explorer engine soon and dont want to waste money on e7's
You will kill someone driving that fast. I have driven alot faster then anyone ever should in these cars. After blowing out a couple of 15 year old tires, I have really calmed down. You will too, or you would get so lucky and it will end itself.
Even since I got married and had a kid, I rarely even go 5mph over.
Absolutely not, that's 158mph...and the fact you can NOT go full throttle in OD...it'll downshift to 3rd. The standard output will NOT pull 4k rpm against an aerodynamic wall in OD...it'd be hard to do it in 3rd. You probably lost 3rd & 4th gears, which is quite common with AOD's. SO makes peak power at 3200rpm...turning anything more than 3800-4000 is a waste.
19# injectors on a SD computer that's calibrated for 14# injectors will certainly cause a rich condition. Whether it'd cause your cutout is a different matter (it certainly wouldn't help), but I still say it's just your lo-po SO 5.0 running out of air. Their power peak, like Sick88 said, is 3200 RPM, so the power will drop off after that and will fall off rapidly at 4000 RPM because the engine just can't move enough air. Remember, 4500 RPM is the (pathetically low) redline of these lumps.
With all else being HO parts (cam, intake, TB, injectors, computer, headers, exhaust) the E7 heads would probably be worth anywhere between 15-25 horsepower. The '86 HO used E6 heads and only made 200 horsepower, while the '87 used E7's and made 225. Not all of that power difference is from the E7 heads though - the '87 also had a larger TB and true dual exhaust with H-pipe, while I believe the '86 Mustang had single exhaust and a slightly smaller throttle body...
i do not have to go WOT to turn 4000rpms, not even 3/4.
this car HAS turned 6500rpm, my brother used to own it and i have personally seen it do it. granted it was in first gear.
Your tach's off, Ford EEC cut the fuel at 6250, it ain't going higher period unless you have a chip to increase the rev limiter... There ain't no maybe about the fuel cut, it's just like you turned off the ign sw...
The AOD will stay in od under full throttle at some point. A couple of years ago I could have told you what point that was.
Why is it that you think that the rest of us; who have been dealing with these particular car and their nuances for
YEARS; are wrong and that you are the only one who is correct?
Accept the limitations of the car. Understand them. Improve upon them.
/thread
Not a stock one...most shift kits won't allow it either...I know....in my old HO/AOD car, 5200rpm in 3rd...would NOT shift into OD...remember governor is 4700...eased off the throttle caught OD and eased back into the throttle...just trying to use enough throttle to maintain speed and it wouldn't happen, downshift right back into 3rd. It just DOESN'T happen.
And even if it did in his car, 150hp is not NEARLY enough to push 3500+ lbs to 160mph.
Sounds to me like a fish story...every time it's told, "it was this big!", your hands get a little further apart.
:rollin:
Yeah, no, a stock AOD will not go into OD at WOT. 4th gear in an AOD is weak and Ford made it impossible to go into 4th at WOT for this reason. 4th is a fuel economy gear, and Ford (rightly) considers that if you wanted fuel economy you wouldn't have your foot to the floor.
Even if it COULD shift into OD (or if it was a T5 and you put it in fifth), you'd lose top end speed because the car doesn't have enough power to push through the air while being overdriven. Most cars, even cars far more powerful than these (which, sadly, would be
"most" cars), achieve their highest speeds in the 1:1 gear (third in an AOD, 4th in a 5-or-6-speed). In other words they're drag limited, not redline limited.
1988 Birdcats are also electronically limited to 110MPH, as previously stated. I think I remember reading a car magazine article years ago in which they managed 123 MPH in an '87 5-speed Turbo Coupe. Anything near 160 mph in one of these isn't going to happen without serious power and aerodynamic enhancements - even if you built a drivetrain to go that fast the car likely wouldn't stay on the ground. Hell, I don't think a C4 Corvette would hit 160 (except the ZR1)...
Carm, the '85 Vette was the first one that GM stated could achieve 150+MPH-- 230 HP, a cD of .33 and a 3.07 ring gear out back..... The old ZR1's were capable of 180.
the tach is correct, i had an aftermarket tach in it and just took it out last week because it was pointless to have.
i wish i had a way to prove my story to be true. the car will turn 4k in drive easily. with a 1:1 drive ratio, 2.73 gears, and 215/60-15's which have a rollout of 75" (roughly 24" diameter) that IS 104mph. it WOULD turn 3k EASILY in OD.
i'm not here to argue guys. i appreciate and value all of your input.
You did say that it was "without a doubt turning 4k in OD"...but your have now corrected your story to 4k in drive, a.k.a. 3rd gear, a.k.a. 1:1.
I'll buy that...the only way that thing could've been to 6500 however is in neutral and the tach needle continued to move even after fuel cut-off at 6250 due to the inertia in the tach...most tach needles can't stop on a dime...especially stockers and cheap junky ones.
i did turn 4k in OD on the night in question
OK, this thread is just getting stupid. We all know it's not possible for several reasons:
- The fact (and these are facts, not opinion) that an AOD will not shift into OD at or anything near WOT
- The fact that the 88 V6 and V8 cars have a speed limiter of 110MPH
- The fact that a stock ECU pulls fuel at 6250 RPM [and the fact that an SO will not spin that fast anyway, fuel cutoff or not]
- The fact that 155 horsepower will not propel a Thunderbird to anything close to 150MPH no matter what gear you're in (as the math would indicate had you indeed pulled 4K in OD).
These all prove that you didn't do it, but you continue to insist that you did it. This is like somebody getting caught red-handed robbing the Quickie-Mart and being shown the video of himself doing it but still denying it in the face of all evidence. The ONLY way your T-Bird approached 150MPH would be if you pushed it out of a helicopter at about 10000 feet. The ONLY ways your tach showed an accurate 6500 RPM would be if (A) You replaced the engine with a Vtec Honda or some other much-more-modern engine than your lo-po 5.0 lump or (B) You have a manual transmission and dropped it into first at 100MPH (and even then you'd likely just drag the rear wheels instead of spinning the engine that fast).
Go ahead, keep bullshiznitting those who know much better. We'll just have a laugh at your expense and never take anything you say in future seriously anyway...
Now, as Paul said, and since this is just insulting the intelligence of this forum as a whole...
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