5.0 HO block/Cobra upper - Poor Acceleration/No Torque, Help
05-23-2011, 02:00 PM
#1
Thread Starter
Join Date: Nov 2007
Posts: 21
5.0 HO block/Cobra upper - Poor Acceleration/No Torque, Help
Hey Guys,
I posted a long while back about this same issue, I've done a lot of trouble shooting/changes since then but still no complete fix. (old post: https://mustangforums.com/forum/5-0l...ight-help.html) Yes that was 3.5 years ago
Been fighting this horse ever since.
In a nutshell: '89 GT HO Block, 94 Cobra upper (GT40 iron heads and U/L cobra intake.) on a '93 Ford Ranger, sas'd D44 front axle 9" rear 4:56 gears on 35's, 4150lb empty. This engine has never had bottom end torque from square 1. Its never ever had the ability to break the tires loose (not even power breaking on packed dirt) even though I've seen plenty of 302 rangers and 35"+ tires that can do burnouts. This engine has GOBS of power above 3,000 RPM. Under that its utterly gutless, my 4.0L V6 would WALK away from this engine from a stoplight by comparison. I have been severely disappointed with this swap.
Originally the engine was built with 24# injectors and 24# pro-m maf. The thing ran pig rich, bought an adjustable FPR to fine tune fuel pressure (mildly helped). The single biggest change that has helped was swapping the 24# injectors and maf for the factory 19# maf (Which is the original from the '89 donor) and put on the 19# injectors. This was an immense improvement in midrange power. This also eliminated my popping through the intake when it was cold! STILL lacks severely power off idle-3000rpm.
The truck was also originally a T-5 later converted to an AOD and problem was consistent with both transmissions (got worse with the auto obviously).
Here is a great video to show you what I'm talking about, This was back with the 24# inj and the T-5. In the video at ~7 seconds I shift to second but hold the clutch in and rev it before dropping the clutch (in some attempt to get it into the power rpms). From 7 seconds on after the rev I drop the clutch in 2nd gear and floor it. The entire time I am going up this hill the throttle is WOT. You can very clearly hear the engine load up and sounds like very retarded timing. It isn't until I crest the hill that it picks up RPM's and you can hear the engine COMPLETELY change pitch as it gets into its power and sound very healthy!
http://www.youtube.com/watch?v=ZcMrI7_BR80
What I've tried:
#Considered issued with ECU, swapped for the A9L for the more aggressive timing tables down low - little to no change.
#Swapped distro out to eliminate pip/tfi - no change
#New cap/rotor/wires/plugs/coil numerous times - no change
#Replaced timing chain to eliminate any slack/cam retard - no change
#Tore engine down to block and replaced all gaskets to eliminate leaks, soaked w/ brake clean to find leaks(none) - no change
#Advanced timing - got to about 14* before it would ping pretty good. I also tried locking it out at ~33* total advance (as far as i got w/o detonation) this obviously helped power but did not fix the bottom end torque issue.
#Tried blocking off PCV system incase it had any vacuum leaks or plumbing was off - no change
#TPS - verified voltages, .98V at idle and smooth flow up to WOT (I forget WOT V reading but it was dead accurate to what i read it should be)
#Codes - only codes I get are for EGR system being gone
#o2 sensors - replaced them at time of engine swap as 1 was bad.
#MAF- I've both replaced and CLEANED both maf's, again the 19# maf made the most improvement but NOT FIXED
Theories-
1)Vacuum issues? I threw a vacuum gauge on her this weekend, only pulls 15" at idle (stock HO cam). It does hold a steady reading at a rev (17"). This seems low to me for a mild build. Shouldn't it be 19-21"? Watch this video (Should it so rapidly drop vacuum and SLAP 0"?)
Vacuum video:
http://s2.photobucket.com/albums/y1/...-08-07_815.mp4
2)Exhaust? My exhaust is smaller than most mustang exhausts as I have to run 1 CAT due to emissions. Running Hedman 302 swap headers 1-5/8" tubes and 2.5" collectors. 2.25" custom Y-pipe to 3" single exhaust, 3" magna flow high-flow cat (clogged maybe from when it ran rich?) and a super 44 flowmaster muffler. Most of you guys run dual 2.5" w/ 3" tips? daul 2.5" exhaust has an area of 9.8sq inches. A single 3" exhaust is only 7.065sq in. Not including the increase with your dual 3" tips.. Thoughts? Maybe the cause of low vacuum? Exhaust is too restrictive?
3)Compression- The gt40 irons have a 64cc combustion chamber vs the 59cc stock dropping compression from 9.5:1 to ~8.8:1. I would think that in an application like mine (heavy truck that needs bottom end grunt) this decrease could be exaggerated. Thoughts? Local machine shop will mill em down for $60/head (PITA tear down in a truck as tall as mine though, those heads are NOT light lol)
4)Cam- from what I can gather the gt40/cobra upper combo really just builds power around 4k RPM. Perhaps a CAM like the XE258 would help me bring that torque curve down into a more usable range in this truck? I've seen a Bronco II with a nearly identical engine except it had the XE258 do a BURNOUT with 40" super swampers! My truck could not break the tires loose if its life depended on it.
5)Sensors? Again codes only indicate EGR issues but perhaps I've got 'defective' sensors giving inaccurate data? Baro? ACT? ECT? I ask about the BARO in particularly because I've noticed that when I drive up to the mountains at much higher elevation this problem is VERY exaggerated. The truck cannot get out of its own way at WOT! When I go up to ski towns to go snowboarding I practically have to wood the damn thing to get it anywhere in town. Does it matter how the BARO sensor is mounted? its mounted on top the plenum in the stock HO plenum. I've relocated it kinda hodge podge on my firewall, sits vertically and at about a 45* angle. ACT has been relocated to my intake tube about halfway between MAF and TB as the Cobra lower doesn't have the port in the #5 cyl. Possible the lower temps are confusing the computer? ECT? The engine does perform even worse in hot weather or even just when its been running a long time and everything has become hot (probably just heat soak into the intake over time).
I really don't know how else to explain how poorly this engine performs from idle-3000 RPM. My 0-60 time is 11 seconds! AWFUL. A factory GT is what 6? I cannot pull away from ANYTHING from a stoplight, grandpa's in 2.2L 2wd yota's walk away from me unintentionally!
My wife's 4.0L Cherokee pulls on my truck by at LEAST 3 car lengths when we race from a dead stop. I can pass her back after 45mph because I get up into the power and it pulls hard.
I am at a total loss and need some new minds to think about this with me! I'm tired of throwing money at sensors/ecu/plugs/wires etc and getting no changes!
Anything helps guys!
I posted a long while back about this same issue, I've done a lot of trouble shooting/changes since then but still no complete fix. (old post: https://mustangforums.com/forum/5-0l...ight-help.html) Yes that was 3.5 years ago
Been fighting this horse ever since.In a nutshell: '89 GT HO Block, 94 Cobra upper (GT40 iron heads and U/L cobra intake.) on a '93 Ford Ranger, sas'd D44 front axle 9" rear 4:56 gears on 35's, 4150lb empty. This engine has never had bottom end torque from square 1. Its never ever had the ability to break the tires loose (not even power breaking on packed dirt) even though I've seen plenty of 302 rangers and 35"+ tires that can do burnouts. This engine has GOBS of power above 3,000 RPM. Under that its utterly gutless, my 4.0L V6 would WALK away from this engine from a stoplight by comparison. I have been severely disappointed with this swap.
Originally the engine was built with 24# injectors and 24# pro-m maf. The thing ran pig rich, bought an adjustable FPR to fine tune fuel pressure (mildly helped). The single biggest change that has helped was swapping the 24# injectors and maf for the factory 19# maf (Which is the original from the '89 donor) and put on the 19# injectors. This was an immense improvement in midrange power. This also eliminated my popping through the intake when it was cold! STILL lacks severely power off idle-3000rpm.
The truck was also originally a T-5 later converted to an AOD and problem was consistent with both transmissions (got worse with the auto obviously).
Here is a great video to show you what I'm talking about, This was back with the 24# inj and the T-5. In the video at ~7 seconds I shift to second but hold the clutch in and rev it before dropping the clutch (in some attempt to get it into the power rpms). From 7 seconds on after the rev I drop the clutch in 2nd gear and floor it. The entire time I am going up this hill the throttle is WOT. You can very clearly hear the engine load up and sounds like very retarded timing. It isn't until I crest the hill that it picks up RPM's and you can hear the engine COMPLETELY change pitch as it gets into its power and sound very healthy!
http://www.youtube.com/watch?v=ZcMrI7_BR80
What I've tried:
#Considered issued with ECU, swapped for the A9L for the more aggressive timing tables down low - little to no change.
#Swapped distro out to eliminate pip/tfi - no change
#New cap/rotor/wires/plugs/coil numerous times - no change
#Replaced timing chain to eliminate any slack/cam retard - no change
#Tore engine down to block and replaced all gaskets to eliminate leaks, soaked w/ brake clean to find leaks(none) - no change
#Advanced timing - got to about 14* before it would ping pretty good. I also tried locking it out at ~33* total advance (as far as i got w/o detonation) this obviously helped power but did not fix the bottom end torque issue.
#Tried blocking off PCV system incase it had any vacuum leaks or plumbing was off - no change
#TPS - verified voltages, .98V at idle and smooth flow up to WOT (I forget WOT V reading but it was dead accurate to what i read it should be)
#Codes - only codes I get are for EGR system being gone
#o2 sensors - replaced them at time of engine swap as 1 was bad.
#MAF- I've both replaced and CLEANED both maf's, again the 19# maf made the most improvement but NOT FIXED
Theories-
1)Vacuum issues? I threw a vacuum gauge on her this weekend, only pulls 15" at idle (stock HO cam). It does hold a steady reading at a rev (17"). This seems low to me for a mild build. Shouldn't it be 19-21"? Watch this video (Should it so rapidly drop vacuum and SLAP 0"?)
Vacuum video:
http://s2.photobucket.com/albums/y1/...-08-07_815.mp4
2)Exhaust? My exhaust is smaller than most mustang exhausts as I have to run 1 CAT due to emissions. Running Hedman 302 swap headers 1-5/8" tubes and 2.5" collectors. 2.25" custom Y-pipe to 3" single exhaust, 3" magna flow high-flow cat (clogged maybe from when it ran rich?) and a super 44 flowmaster muffler. Most of you guys run dual 2.5" w/ 3" tips? daul 2.5" exhaust has an area of 9.8sq inches. A single 3" exhaust is only 7.065sq in. Not including the increase with your dual 3" tips.. Thoughts? Maybe the cause of low vacuum? Exhaust is too restrictive?
3)Compression- The gt40 irons have a 64cc combustion chamber vs the 59cc stock dropping compression from 9.5:1 to ~8.8:1. I would think that in an application like mine (heavy truck that needs bottom end grunt) this decrease could be exaggerated. Thoughts? Local machine shop will mill em down for $60/head (PITA tear down in a truck as tall as mine though, those heads are NOT light lol)
4)Cam- from what I can gather the gt40/cobra upper combo really just builds power around 4k RPM. Perhaps a CAM like the XE258 would help me bring that torque curve down into a more usable range in this truck? I've seen a Bronco II with a nearly identical engine except it had the XE258 do a BURNOUT with 40" super swampers! My truck could not break the tires loose if its life depended on it.
5)Sensors? Again codes only indicate EGR issues but perhaps I've got 'defective' sensors giving inaccurate data? Baro? ACT? ECT? I ask about the BARO in particularly because I've noticed that when I drive up to the mountains at much higher elevation this problem is VERY exaggerated. The truck cannot get out of its own way at WOT! When I go up to ski towns to go snowboarding I practically have to wood the damn thing to get it anywhere in town. Does it matter how the BARO sensor is mounted? its mounted on top the plenum in the stock HO plenum. I've relocated it kinda hodge podge on my firewall, sits vertically and at about a 45* angle. ACT has been relocated to my intake tube about halfway between MAF and TB as the Cobra lower doesn't have the port in the #5 cyl. Possible the lower temps are confusing the computer? ECT? The engine does perform even worse in hot weather or even just when its been running a long time and everything has become hot (probably just heat soak into the intake over time).
I really don't know how else to explain how poorly this engine performs from idle-3000 RPM. My 0-60 time is 11 seconds! AWFUL. A factory GT is what 6? I cannot pull away from ANYTHING from a stoplight, grandpa's in 2.2L 2wd yota's walk away from me unintentionally!
My wife's 4.0L Cherokee pulls on my truck by at LEAST 3 car lengths when we race from a dead stop. I can pass her back after 45mph because I get up into the power and it pulls hard.
I am at a total loss and need some new minds to think about this with me! I'm tired of throwing money at sensors/ecu/plugs/wires etc and getting no changes!
Anything helps guys!
05-24-2011, 07:58 AM
#2
Thread Starter
Join Date: Nov 2007
Posts: 21
One other thing I forgot to mention was a compression test, all cylinders came in between 155-165.
And now that I really think about it, I think my Y-pipe is actually 2" piping, its rather small.
Any thoughts? Suggestions?
Thanks!
And now that I really think about it, I think my Y-pipe is actually 2" piping, its rather small.
Any thoughts? Suggestions?
Thanks!
05-25-2011, 03:00 PM
#3
Join Date: Mar 2011
Location: Illinois
Posts: 3
I was having the same exact issue with my engine, I did just about everything you did as well, all sensors are new, my issue was needing a bigger fuel pump, injectors, MAF, and finally the computer. the computer fixed the issue, I have an 88 5.0 stang but engine has been upgraded to a 347. The computer on my stang couldn't be adjusted so I had to get a different one that worked with the MAf sensor. I couldn't burn my tires IN THE RAIN mine dogged out so bad.
05-25-2011, 03:58 PM
#4
Thread Starter
Join Date: Nov 2007
Posts: 21
Interesting, What computer did you put in? And what Injectors/Maf are you running?
I replaced my ecu already with the A9L, made no difference. I am using the stock Ranger fuel pump... from what I can find its comparable/identical to a stock mustang fuel pump which from what I can find is 88lph? Maybe this is a problem? Many mustang guys run 155/190lph no? I would suspect if it was fuel delivery that it would fall apart/sputter on the top end or would it be more noticeable on the bottom end if there is lack of fuel flow?
And mine is exactly the same way, I cannot burn out even when its pouring rain and standing water on the ground.
I replaced my ecu already with the A9L, made no difference. I am using the stock Ranger fuel pump... from what I can find its comparable/identical to a stock mustang fuel pump which from what I can find is 88lph? Maybe this is a problem? Many mustang guys run 155/190lph no? I would suspect if it was fuel delivery that it would fall apart/sputter on the top end or would it be more noticeable on the bottom end if there is lack of fuel flow?
And mine is exactly the same way, I cannot burn out even when its pouring rain and standing water on the ground.
05-26-2011, 10:53 AM
#6
Thread Starter
Join Date: Nov 2007
Posts: 21
Is it possible to have bad leak down and still have decent compression? When I did my compression test all cylinders came in around 155-165. I'll figure out which is cheaper, either rent a leak down gauge from my local part shop or just build my own. They look easy enough to build, just need some kind of regulator to feed a consistent 100psi and a pressure gauge past it to read pressure in the line/system %'s would be easiest to figure off hand when feeding 100psi :P
I'll look into this, the other thing I'm considering now is my fuel pump. I didn't realize its only 88lph at best. The stock Cobra fuel pump is 110lph, that's already 22 over. Perhaps this is what dropping down to 19# injectors IMPROVED performance because the pump isn't working as hard? Thoughts? Its also the factory fuel pump with 220k miles on it!
I'll look into this, the other thing I'm considering now is my fuel pump. I didn't realize its only 88lph at best. The stock Cobra fuel pump is 110lph, that's already 22 over. Perhaps this is what dropping down to 19# injectors IMPROVED performance because the pump isn't working as hard? Thoughts? Its also the factory fuel pump with 220k miles on it!
05-26-2011, 07:16 PM
#7
Join Date: Mar 2011
Location: Illinois
Posts: 3
We installed a new BBk 255 lph fuel pump, adjustable pressure regulator, 30lb injectors and the A9P ECU. Every engine builder we spoke to said that is what we needed. It's running fantastic now. Just an FYI also, the lack of fuel will eventually cause detonation from the lack of fuel. that's what cracked my pistons. Jeggs has everything we bought for around 600. Hope this fixes your problem for you, please let me know if that's what the issue was if you decide to go the fuel route.
05-26-2011, 08:01 PM
#9
4th Gear Member
Join Date: Jul 2008
Location: alabama
Posts: 1,812
If you still have the aod how about running the right ecm A9P, A9L is for a 5spd! is the fpr working properly!? We just went thru this issue on my buddies 331, if you floored it and held it it wouldnt do **** if you rolled on it, it would go and about 3500 pull like it should.
He finally listened and got a new fpr and the car runs fine now no other issues!
Hook up a test gauge and see what the pressure is doing under throttle! idling should be about 38 wot about 42-43lbs.
Your 2 in exaust is definatly a choke but it would cause it to get worse higher in the rpm range if that was it!
Your vac will drop to nothing at wot! you only have vac idling or constant cruise!
He finally listened and got a new fpr and the car runs fine now no other issues!
Hook up a test gauge and see what the pressure is doing under throttle! idling should be about 38 wot about 42-43lbs.
Your 2 in exaust is definatly a choke but it would cause it to get worse higher in the rpm range if that was it!
Your vac will drop to nothing at wot! you only have vac idling or constant cruise!
05-27-2011, 01:37 PM
#10
Thread Starter
Join Date: Nov 2007
Posts: 21
Sorry it IS the A9P! The auto computer with the more advanced timing tables <3k rpm for the AOD.
I'm really starting to wonder if it is my fuel pump. This build aught to be putting a solid 250HP to the ground/300HP at the crank and using the below table for fuel pump guides its WELL under!
-----------
To determine the overall capacity of a fuel pump rated in liters, use the additional following conversions:
(Liters per Hour) / 3.785 = Gallons
Multiply by 6.009 = LBS/HR
Multiply by 0.9 = Capacity at 90%
Divide by BSFC = Horsepower Capacity
So for a 110 LPH fuel pump:
110 / 3.785 = 29.06 Gallons
29.06 x 6.009 = 174.62 LBS/HR
174.62 x 0.9 = 157 LBS/HR @ 90% Capacity
157 / 0.5 = 314 HP safe naturally aspirated “Horsepower Capacity”
Here's a chart for those of us too lazy to do the math or don't have a calculator handy...
Safe “Horsepower Capacity” @ 40 PSI with 12 Volts
60 Liter Pump = 95 LB/HR X .9 = 86 LB/HR, Safe for 170 naturally aspirated Horsepower
88 Liter Pump = 140 LB/HR X .9 = 126 LB/HR, Safe for 250 naturally aspirated Horsepower
110 Liter Pump = 175 LB/HR X .9 = 157 LB/HR, Safe for 315 naturally aspirated Horsepower
155 Liter Pump = 246 LB/HR X .9 = 221 LB/HR, Safe for 440 naturally aspirated Horsepower
190 Liter Pump = 302 LB/HR X .9 = 271 LB/HR, Safe for 540 naturally aspirated Horsepower
255 Liter Pump = 405 LB/HR X .9 = 364 LB/HR, Safe for 700 naturally aspirated Horsepower
--------------------
I think a 155LPH pump would be FAR more ideal! Can pick one up for like $75 new from mustangs unlimited/jegs/etc
I think this may explain 2 things, 1 the lack of low end power and 2 high end detonation with mild timing advance. When I ran 87 Octane I could not advance it past 10*, it would ping at 11*. With 91 Octane (which i run currently) I can only get it up to about 13/14* before it detonates. Even so at 13/14 on 91 octane on a hot day it will detonate above 4-4500 or so. This seems odd compared to what I see most of you getting out of your engines as far as timing.
What do you all think? and since I have a pickup - 6 bolts and the bed comes off giving me instant access to the pump! :P
I'm really starting to wonder if it is my fuel pump. This build aught to be putting a solid 250HP to the ground/300HP at the crank and using the below table for fuel pump guides its WELL under!
-----------
To determine the overall capacity of a fuel pump rated in liters, use the additional following conversions:
(Liters per Hour) / 3.785 = Gallons
Multiply by 6.009 = LBS/HR
Multiply by 0.9 = Capacity at 90%
Divide by BSFC = Horsepower Capacity
So for a 110 LPH fuel pump:
110 / 3.785 = 29.06 Gallons
29.06 x 6.009 = 174.62 LBS/HR
174.62 x 0.9 = 157 LBS/HR @ 90% Capacity
157 / 0.5 = 314 HP safe naturally aspirated “Horsepower Capacity”
Here's a chart for those of us too lazy to do the math or don't have a calculator handy...
Safe “Horsepower Capacity” @ 40 PSI with 12 Volts
60 Liter Pump = 95 LB/HR X .9 = 86 LB/HR, Safe for 170 naturally aspirated Horsepower
88 Liter Pump = 140 LB/HR X .9 = 126 LB/HR, Safe for 250 naturally aspirated Horsepower
110 Liter Pump = 175 LB/HR X .9 = 157 LB/HR, Safe for 315 naturally aspirated Horsepower
155 Liter Pump = 246 LB/HR X .9 = 221 LB/HR, Safe for 440 naturally aspirated Horsepower
190 Liter Pump = 302 LB/HR X .9 = 271 LB/HR, Safe for 540 naturally aspirated Horsepower
255 Liter Pump = 405 LB/HR X .9 = 364 LB/HR, Safe for 700 naturally aspirated Horsepower
--------------------
I think a 155LPH pump would be FAR more ideal! Can pick one up for like $75 new from mustangs unlimited/jegs/etc
I think this may explain 2 things, 1 the lack of low end power and 2 high end detonation with mild timing advance. When I ran 87 Octane I could not advance it past 10*, it would ping at 11*. With 91 Octane (which i run currently) I can only get it up to about 13/14* before it detonates. Even so at 13/14 on 91 octane on a hot day it will detonate above 4-4500 or so. This seems odd compared to what I see most of you getting out of your engines as far as timing.
What do you all think? and since I have a pickup - 6 bolts and the bed comes off giving me instant access to the pump! :P