Engine '88 GT Has No Power Above 3000 RPM After Trick Flow 11r Heads Install

JRerecich

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Feb 12, 2020
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Hey all! I have been using this forum for the last few months getting information, which has helped a lot, but my dad and I are finally scratching our heads on this one. A little background on the car. We have an 88' GT that has been completely stock besides an e303 cam and a mass air flow conversion my dad installed a few years ago. Before we did this project we made sure the car was healthy, so we took it to our tuner to get it dynod. The car made 217 hp to the wheels. The last few weeks we have been installing all sorts of new parts to get the most performance we can while n/a and before we pull the motor. The car idles good, but completely falls on its face above 3000 rpm. Here is the list of the parts we've installed:

Trick Flow 11r 190cc heads
Trick flow track heat intake
e303 cam
24# injectors with BBK MAF
Accufab 65mm throttle body with EGR delete spacer
1.7 roller rockers
Lengthed push rods
Billet MSD distributor
Ford racing spark plug wires
Autolite spark plugs
SVE radiator with electric fans
140 amp alternator
New MAP sensor
A/C, Smog pump, & Charcoal canister have been deleted

Now, when we put the roller rockers in, we made sure that our rocker geometry was perfect. Put cylinder #1 at TDC and as soon as the exhaust valve went down we put the intake rocker in, then put the exhaust rocker on when intake just started to open. We followed that procedure for the H.O firing order. We are having a hard time believing it is valve related, but will double check later. The only codes being thrown are for the EGR and Smog pump. We also did a cylinder balance check and received a 90 on the first test. Our vacuum gauge reads pretty much a steady -14 at idle and goes up to -20 when throttle is held at 2500 rpm. Our AFR gauge reads pretty lean (around 18 or so at idle and 15 or so at cruise) so we figured our problem was it wasn't getting enough fuel. We just took it to our tuner today and he said it was severely under powered after tuning the fuel (Only about 160 hp to the wheels).

We aren't sure where to look at now, because we don't want to start throwing parts at knowing it ran great before we did all this. I was thinking it may be due to it not having enough fuel pressure, so I might hook up a fuel pressure gauge later to see. Any help would be greatly appreciated, thanks!
 
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John Dirks Jr

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Does this car have a chip in the ECU? I ask because you said the tuner tuned the fuel. I'm wondering how he did this. And I'm wondering why the "tuner" would not have insight about the low power output.

Will the engine rev up under load to the desired rpm or does it stumble or die off at a lower than desired rpm?
 

JRerecich

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Yes, I forgot to mention it does have a chip. Engine sounds great revving up and it doesn't stumble or die at all, just no power at higher rpm. We just met with him in-person. Firstly, he said to check our push rod length, because maybe we mis-measured it as the car was sitting for a couple weeks before we measured. I just got done taking cylinder #1 rockers off and the wear mark is dead center on the top of the valve spring. Secondly, he said we should look into getting an msd box, because it seems like its not getting ennough spark, but I am not familiar with those, so it seems odd I would need one now when the car ran great before without one. I just drove the car around and, to me, it almost seemed as if the clutch was starting to slip once I got into the higher rpms. I can't say for sure it was or wasn't, but could these symptoms be the culprit of a slipping clutch?
 

John Dirks Jr

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If the clutch was slipping, the engine rpm would shoot up rapidly and at this same time, the car would loose forward momentum and acceleration.
 

JRerecich

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I'm going to test it tomorrow by putting it into 4th or 5th at low speed and going wot. I just cannot for the life of me think of why it loses so much power at the higher end of the rpm. It definitely feels slower than before.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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I think this 'turner' guy is not right for you. you don't need a msd box.
I doubt you even need a chip.
Check compression, and timing and verify fuel pressure first then the knowledgeable members can help you better.
 
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JRerecich

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I think this 'turner' guy is not right for you. you don't need a msd box.
I doubt you even need a chip.
Check compression, and timing and verify fuel pressure first then the knowledgeable members can help you better.
I mean this guy has worked on multiple fox bodies before and I even think he dragged one, so he seems legit. Fuel and timing are good, I will be checking compression this weekend.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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I mean this guy has worked on multiple fox bodies before and I even think he dragged one, so he seems legit. Fuel and timing are good, I will be checking compression this weekend.
Take no offense to this but I like to see numbers and verification of events. Too many times I've read 'timing is good' when in fact they are relying on a 30 year old balancer that has slipped and reading wrong, same with 'fuel pressure is good' when they only pushed the schrader valve and fuel squirted out.
Verify your timing is correct and fuel pressure is set and does not fluctuate when you rev it up and your compression is good.
 
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John Dirks Jr

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Try a 3rd gear pull to check clutch holding ability. Start the test from a 40mph roll in third. Floor it. It should climb steady to 70 or 80 mph. If the clutch fails to hold, rpm will shoot suddenly up and the vehicle speed increase will stop.
 
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JRerecich

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Try a 3rd gear pull to check clutch holding ability. Start the test from a 40mph roll in third. Floor it. It should climb steady to 70 or 80 mph. If the clutch fails to hold, rpm will shoot suddenly up and the vehicle speed increase will stop.
Thanks, I will try that out!
 

John Dirks Jr

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Exactly what is your base timing at (spout removed)?

Did you change Maf or anything else with the air intake tubing or filter?

Be aware that some combinations of tubing, filters, varies Maf designs don’t always work well together. Sometimes the Maf just needs to be rotated to a different position I sense the air volume properly.
 
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JRerecich

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Exactly what is your base timing at (spout removed)?

Did you change Maf or anything else with the air intake tubing or filter?

Be aware that some combinations of tubing, filters, varies Maf designs don’t always work well together. Sometimes the Maf just needs to be rotated to a different position I sense the air volume properly.
Timing is set to 14 degrees. Air intake tubing, maf placement, and filter have been left exactly the same when we pulled it off.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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Fuel pressure: 32-35lbs at idle with vacuum line connected, 42-46 with vacuum line off and plugged. 42-46lbs when revving up.
TIming: varies, most like 12-14* btdc, remember to pull the spout.
Compression: 150 psi +/- 10% variation I think is acceptable.
Note: I noticed you are using a E cam with 1.7 rocker arms. Did you verify piston to valve clearance?
 
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JRerecich

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Fuel pressure: 32-35lbs at idle with vacuum line connected, 42-46 with vacuum line off and plugged. 42-46lbs when revving up.
TIming: varies, most like 12-14* btdc, remember to pull the spout.
Compression: 150 psi +/- 10% variation I think is acceptable.
Note: I noticed you are using a E cam with 1.7 rocker arms. Did you verify piston to valve clearance?
Ok thanks, I will recheck everything and double check it matches that. No, we did not verify piston to valve clearance.
 
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Aug 11, 2019
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Few things. Why on earth,after all those mods you stayed with an E303? Ancient cam technology,car would be so much better with a current grind. And what exactly do you mean by car just "falls on it's face". What does it do?
 

JRerecich

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Few things. Why on earth,after all those mods you stayed with an E303? Ancient cam technology,car would be so much better with a current grind. And what exactly do you mean by car just "falls on it's face". What does it do?
We will be going to a 347 in about a year or so, so no need to have a custom cam grinded when will be doing that once we pull the engine. It basically stops pulling hard like it should past 3k. It was only putting down about 180 whp yesterday on the dyno.
 

Gs87GT

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What exhaust are you running? Stock? Cats? Could something have fallen into the exhaust and partially blocked it during the head swap? ? Bad cats if you have them?
 

John Dirks Jr

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you say, “stops pulling hard at 3000rpm”

Does that mean the rpm reaches 3k and won’t increase above that?

Since you were on the dyno yesterday, you have other data instead of just hp I’m sure. So, what’s happening with the fuel pressure and AF mixture when it “stops pulling hard at 3k”?