SD issues after ported GT40 swap 5.o ho cam

jetski247

jetski247

Member
ive read a ton of threads that say the speed density runs good on mustang ho cam and gt40's.

well i have a set of ported gt40's with larger chevy 1.9 intake and larger (can't remember) exhaust valve. ported to 1250 and FMS shorties. nothing special, installed a 5.o ho cam from an 86.

the problem im having is the same problem i had running a custom ground cam for all the parts i have. it dies when you put it in gear or come up to a stop. idle purrs like a kitten, starts right up with what seems like no issues, no cel until i drive it around for about 20 minutes which may be the issue.

idle vacuum in park is 17 and in gear starts to ramp up and down around 15/14 which from what i remember was very close to the stock cam and e7's i took off.

active code that throws the cel on after a while is 121
inactive codes are 118, 172, 327 and 332

it was running a custom ground cam on maf until my baumanator quit working so i switched back to sd to drive the truck until i figure out if i want to leave it stock or keep messing with all the performance stuff.

so i wanted to see what sd could handle and tried to run it but i guess it did not like the 112deg lobe seperation of the custom ground cam. so i swapped in a 5.o ho cam and it runs exactly the same, no difference what so ever, even has the same problem of dieing when putting in gear and coming up to a stop.

so my question is...............if i put the truck cam back in (which is a 95 roller cam) will the ported heads give me the same problems im having? im not working right now and have some time to swap everything.

95 f150 5.8 e4od, bbk twin 56, v10 tb spacer, edelbrock truck upper/lower, gt40 ported/large valve heads, fms shorties
 
jetski247 said:
ive read a ton of threads that say the speed density runs good on mustang ho cam and gt40's.

well i have a set of ported gt40's with larger chevy 1.9 intake and larger (can't remember) exhaust valve. ported to 1250 and FMS shorties. nothing special, installed a 5.o ho cam from an 86.

the problem im having is the same problem i had running a custom ground cam for all the parts i have. it dies when you put it in gear or come up to a stop. idle purrs like a kitten, starts right up with what seems like no issues, no cel until i drive it around for about 20 minutes which may be the issue.

idle vacuum in park is 17 and in gear starts to ramp up and down around 15/14 which from what i remember was very close to the stock cam and e7's i took off.

active code that throws the cel on after a while is 121
inactive codes are 118, 172, 327 and 332

it was running a custom ground cam on maf until my baumanator quit working so i switched back to sd to drive the truck until i figure out if i want to leave it stock or keep messing with all the performance stuff.

so i wanted to see what sd could handle and tried to run it but i guess it did not like the 112deg lobe seperation of the custom ground cam. so i swapped in a 5.o ho cam and it runs exactly the same, no difference what so ever, even has the same problem of dieing when putting in gear and coming up to a stop.

so my question is...............if i put the truck cam back in (which is a 95 roller cam) will the ported heads give me the same problems im having? im not working right now and have some time to swap everything.

95 f150 5.8 e4od, bbk twin 56, v10 tb spacer, edelbrock truck upper/lower, gt40 ported/large valve heads, fms shorties
Click to expand...

Code 121 is a tps voltage issue it seems. To me that goes hand in hand on the behavior you're seeing. What have you done to fix that?
 
Yep, the problem is the computer isn't sure what's going on with the throttle, so the idle air control valve and probably the timing isn't responding correctly.

The truck doesn't know it's supposed to be idling.

Sent from my LM-G820 using Tapatalk
 
after my 10mo takes a nap im going to test tps voltage. another thing i thought was maybe a pin got pushed out when i installed the ecm, several tabs to lock in the pins were broken so i zip tied the wires with the broken tabs to the wire next to it without a broken tab to help hold in in place. when i went to sd i removed my a9p for the jog1 i have so those are the 2 things im going to check.....

tps voltage
pushed eeciv pin

i soldered a wire to the black tps wire the last time i replaced it so i can check pretty quickly, i also drill out the mounting holes in the sensor and make them more elongated so i can move it around if i need to.
 
i made a video of whats going on, waiting for it to upload.
"edit" vid is at bottom of post

so i tested the tps and:

first i got nothing, then made sure my key is on, then i start checking fuses and still nothing..........dead, so I unplug the sensor and check the pins and get 5.0v, plug it back in and nothing.............and im like WTF??

so i just happen to open the throttle all the way to see my volt tester get a reading...........and i was like, thats wierd?

i get no voltage at all until about 1/2 throttle, it starts around 2.5v and goes up to about 3.3v "ish" at wot. then im like, well theres my problem.........

so i think no big deal, ive got 3 other tps sensors (all used) but i'll test those whilst everything is open and pick the best one.................and every singe one did the same thing. exact same voltage, starts about 1/2-3/4 throttle at about 2.5ish then maxes out about 3.o depending on the sensor i tested but even my motorcraft one did the same thing.................so now im like maybe my pins got pushed out???

so then i look at the pcm to make sure that the three wires are seated in the pcm all the way, which they were.

so im going to go get another one and see what it does.

could a burnt capacitor on the ecm cause this? it didnt throw those codes with the a9p

heres a vid https://youtu.be/Q2oaQQrMqFw
 
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jetski247 said:
i made a video of whats going on, waiting for it to upload.

so i tested the tps and:

first i got nothing, then made sure my key is on, then i start checking fuses and still nothing..........dead, so I unplug the sensor and check the pins and get 5.0v, plug it back in and nothing.............and im like WTF??

so i just happen to open the throttle all the way to see my volt tester get a reading...........and i was like, thats wierd?

i get no voltage at all until about 1/2 throttle, it starts around 2.5v and goes up to about 3.3v "ish" at wot. then im like, well theres my problem.........

so i think no big deal, ive got 3 other tps sensors (all used) but i'll test those whilst everything is open and pick the best one.................and every singe one did the same thing. exact same voltage, starts about 1/2-3/4 throttle at about 2.5ish then maxes out about 3.o depending on the sensor i tested but even my motorcraft one did the same thing.................so now im like maybe my pins got pushed out???

so then i look at the pcm to make sure that the three wires are seated in the pcm all the way, which they were.

so im going to go get another one and see what it does.

could a burnt capacitor on the ecm cause this? it didnt throw those codes with the a9p
Click to expand...

Do you have a steady 5v? You might have issues with your vREF circuit. So there's the TPS out that most usually check, but you need to check the 5v supply as well.
 
Did you move the wires around while checking? Do you have 5v when the signal goes to 0?
 
Is there anything out of sorts with the mechanical doomaflitchy that turns the tps? What if you turn the tps (plugged in of course) with a screwdriver?

Sent from my LM-G820 using Tapatalk
 
Sorry for the confusion
If I unplug the TPS I get constant 5v like normal. No fluctuations at all.
When I plug the TPS back in I'm trying to read reference voltage (I think that's what it's called) which should be just under 1v (usually around (.5-.9)which I get nothing until about 1/2 throttle.
I tried all 4 sensors by turning the dumaflatchy by hand and watching my meter and they all do the same.
I'm back probing the green wire of the TPS and grounding to the battery.
Wether or not it bolted to the throttle body or not I get the same result. I'm either doing the test wrong or every sensor I have is bad.

Did y'all see the vid?
Here is the reference write up I'm following: https://www.fullsizebronco.com/threads/throttle-position-sensor-testing-replacement-and-adjustment.203080/
 
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You need to use the sensor ground for ground not the battery. Sensor ground is the ECU.

If it were mine this is what I would do first re-run the test using the sensor ground as the ground for your test light and make sure you have 5 V supply through all the range of motion with the TPS on the throttlebody. Then test the TPS signal the same way.
 
Ok, I'll do that today.
So hook everything up and see if I get steady 5v throughout the range, and if so my 12v supply is good, if not it's bad
Second, check return signal to see what it's sending to the puter.

I made a splice on the black wire in the past so I could test it while it's hooked up but that wire was dead throughout the test.
 
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ok, who came over in the middle of the night and fixed it?

i put little bit down for a nap, go out and pop the hood and get ready to start testing........

so with everything hooked up, reference voltage with my meter showed 5.2v at idle all the way through wot.
so next test, signal return. i get .94v at closed and 4.62 at wot, and im like.........uh.......wtf? i did nothing to anything. so i start it up and vacuum at idle is right at 20 which is what it was with the stock cam and e7's so im thinking this puppy is going to work this time.

so next test, test drive. it died 10 times just trying to get out of the driveway but i disconnected the negative to reset everything so maybe its just learning. so i give it a little throttle and take it on a 30 minute cruise to see if any cel's pop up, which did within the first 20 feet of driving. still, drove it around for 30 minutes, get home, dies in driveway, (its surging up and down while in gear) and i check codes and now i only get a 626, which is coast clutch solenoid.

so nothing engine related popped up but now that the tps automatically fixed itself, do you think the same guy who snuck over here last night and fixed it will return and fix the surging idle in gear issue? which may be cam and heads (hint hint) the e7's are in the shopping kart in the garage along with 3 stock roller cams.

besides that, i used an actual meter this time instead of the snap-on voltage/test light thingy. which i should have grabbed it to see if that was what was the issue but it still gave me codes yesterday which were tps related and not today.

so who knows whats actually going on or what happened. performance wise, no difference at all in power and torque (actually a loss) compared to the stock cam and heads which are going back on if it keep dieing with no codes.
 
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ok, cam is going to come out i guess, still dies when in gear and sometimes when coming up to a stop.626 was a pushed out pin, brown/orange stripe was pushed out which is the bottom side, fender side so i couldnt see it until i pulled my fender liner out and there is was, still in the silicone seal but def pushed out.

koeo test now is 111 . 172 332

as soon as i drive off, cel pops up and stores 172 and 332. i tried moving the o2 sensor on the passanger side header up real close to see if that made a difference but no dice on that. EGR im not sure, i cleaned it out, took it apart, checked everything, vacuum line held, replaced with another doner ive got but no dice on that either, says insufficient flow.

extra flow may be effecting the lean code and egr flow? hell i don't know......

not sure if more air is needed for the iac? not sure what the idle iac trick is, was told to set it with it unplugged? i tried to research that but didn't find anything.

so stock cam is going back in, going to try and make a magnetic lifter holder mabob. ive got a bunch of flywheel magnets from jet ski flywheels that are really strong, i hate taking the stupid intake manifold off every time. the spider would be the culprit since its always pushing down on them.
 
Setting the idle isn't a trick, just a procedure. You warm the engine up to operating, unplug the iac, and then set the idle to your low idle setpoint (~700-750) using the idle set screw on the throttle body.

This means that this RPM is the minimum level the engine can ever idle at and the iac is used solely to increase the idle above that. It's the way it's intended to work.
 
I guess I read that wrong. I was told to set the idle screw so the butterfly s are closed and idle soley upon the iac but I'll do that today. I'm wondering if my custom ground cam from cam research will work now because it gave me the exact same issues.

It's got 112* love separation and ran good minus the same thing it's doing now. He told me it will run on speed density which it did. I've got some vids of how it drove in this heavy truck.

So I guess I'll set idle, then reset TPS and go from there, I can't believe all this time I've been doing it backwards...lol
 
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