SILVE2BACK

Today while driving my new engine hit WOT while I was idling in a left hand turn lane. I was able to steer into a field on the right hand side of the street and thought for a minute about stopping my Camaro in a tree (its a 68 nooo man nooo!) but I was able to throw it in Park and turn it off. I popped the hood and noticed the Throttle body was closed. On restart it hit WOT again with no gas applied. I tapped the gas a few times and it broke out of WOT. Is it possible for a faulty TPS to cause this? I know there is a limp mode to prevent it but it is a Custom LS1 in a 68, not everything is perfect.

Old Geezer

iTrader: (3)

Drive by wire?
If so, could be someone has fubared the throttle tune.
Put the response out of range, and the throttle becomes uncontrollable.
What's this mean? "not everything is perfect."

SILVE2BACK

Well Drive by wire? I am not thinking it is full that since the throttle bodies air flow is controlled by the gas pedal cable that also controls the tps level. Which means if the TPS read WOT at... 5v's? the air flow would still be restricted at closed throttle since the throttle body would still be closed if it is malfunctioning.

Not everything is perfect, I mean since it is a custom Job there are some.... custom setups. I experienced a really bad situation with the builder I am still trying to recover from and I am an old school distrib/carb guy. That is what my dad taught me. This LS1 is new to me. I'll share the current document.

https://www.dropbox.com/s/skp0m5z279...ement.pdf?dl=0

truckdoug

iTrader: (25)

there are two types of throttle bodies generally in the LS world

DBW drive by wire = the throttle is electronically operated by a dc stepper motor on the throttle body itself.

DBC drive by cable, a mechanical cable that goes from the gas pedal to the throttle body

that is what chuck was asking.

SILVE2BACK

Thank's Doug, I was unaware.

This is the Throttle Body I installed.
https://www.summitracing.com/parts/pfs-69726

Looking into the differences I would say it's drive by cable.

firstgenon24s

iTrader: (1)

I'm sorry dude, I don't have much insight but I read through your nightmare and it really sucks and its very unfortunate that shops take advantage of people like they did you. I hope all goes well in your favor and I hope you at least have fun with the car!

SILVE2BACK

Thank's man, the only good thing that came out of it is I was FORCED to learn these things on the new engine. That I am not sad at but the nightmare, I would have skipped if I had known. The Tuner Carl that came by really was a stand up guy. He helped me way more than someone should have had to for the price I paid him.

70 Bug Mid Engine

I have had issues with the China throttle bodies (Procomp and Profession Products). Nothing like fully opening from idle but more of automatically opening past 1/2 throttle and not closing until the car is off. If anything, you may want to try winding the return spring another turn but if it was me, I would replace it with an Accufab or FAST. Shoot, even a stock GM one would do the trick.

truckdoug

iTrader: (25)

maybe add an assist spring?

really the only thing that could cause a stuck WOT is a mechanical malfunction like ^^^ this fella says

truckdoug

iTrader: (25)

and yes the learning curve on these motors is steep, but hang tough. the rewards are plenty of reliable power for fair money.

SILVE2BACK

Hmm thanks for the input you two. I will look into an assist spring. Maybe even replace the throttle body. I would hate to have to tune it again to a new TB but safety is more important.

imma_stocker

iTrader: (19)

Tune is cheaper than driving into a tree. Just like correct cable tension and lubricating the throttle cable is important to relieve cable "catching" in the sheath.

Being cable operated throttle you have mechanical issues (easier to fix IMO). Tighten up the return spring by rotating another round and/or add an assist spring if possible.

My old FAST 92 was tightened without another spring. My current accufab 4150 (carb style throttle for EFI) has 2 return springs along with the built-in return.

SILVE2BACK

Isn't that the truth, I am thinking about getting the HP Tuners Suite and learning to tune the Ls1's myself. I use to be able to twist the distrib, fiddle with a few screws on the carb, flash a light and listen to get it where I wanted it. Now if I replace a throttle body it's a 500 tune! lol man!

Will WD-40 be fine for the cable lube?

imma_stocker

iTrader: (19)

WD-40 works ok for cable lube.

Check this out.... same concept.
http://www.motorcyclistonline.com/mo...c-garage-video

SILVE2BACK

Thanks for this, I will make sure to lube up that throttle cable, I did get it to catch while playing with it and watching under the hood. So the TPS is no longer the worry.

fst100

iTrader: (5)

could also be a stuck TPS (spring stuck or caught somewhere). if the cable's not at fault/sticking.

SILVE2BACK

I finally figured out what was going on. The pedal assembly comes up at the back of the engine bay driver side. There is a custom bracket on the rear driver side of the LS1 mounted on the intake bolt next to the fuel rail for the throttle cable. The throttle cable clamp is about... 1/2 inch in diameter. so on occasion when the throttle was released that 1/4 inch would hang up on the fuel rail on return. leaving me about I am guessing 20-30% throttle... enough to spin them while the brakes were applied and inching me forward.

Since I currently do not get full throttle anyway I simply bent the throttle pedal arm to a 45 away from the fuel rail. This stopped it from hanging up.

However, I now need to find a replacement throttle pedal that will fit into a 68 Camaro bay with an LS1. I will get and supply pictures. Its this or I need to find something that will magnify my current lever travel to the throttle cable. Honestly, I hate the way the pedal feels atm so I will be replacing it.

Any thoughts on a good throttle setup?

imma_stocker

iTrader: (19)

What throttle cable are you using? Looking at the picture it looks like there is some adjustability there. Maybe a different cable bracket or modify the geometry to work 100%.

Or drill the pedal to modify pedal:cable travel ratio?

Aftermarket pedals get into lots of measure this, measure that, measure everything again, guesstimate pulley ratio, etc. THEN you still have to spend time tweaking it (have a helper operate the pedal while tweaking).
https://www.classicindustries.com/sh...edal-assembly/
Not a clue which of these would work for you.

SILVE2BACK

Thanks for your help. I measured around and looked at the clearances. I am currently using a stock pedal. Since it is behind the engine the travel is just not far enough with the tension and play in the pedal to pull it back to wot.

I decided to go with this
https://www.classicindustries.com/pr...s/bag6004.html

It looks like I could mount it pretty easily in an open area on my firewall and do away with the weird angle of the stock pedal that creates the play over time. I can also hook up their throttle cable. I need about 4 feet to get it into proper position so I ordered the 48 inch LS1 version by Lokar as well.

It looks like this, with my sons help, can fix the issue. Should be here by Friday, I will make him mess with it with me till it's not catching and opening right. It will be nice to be rid of this issue.

SILVE2BACK

Install of new pedal went well this weekend. Random Wots seems to have stopped completely as expected. I made sure all clearances and stick points were gone. It does get full range of throttle now and the TV cable works as it is suppose too. All in all this was a great... upgrade to fix a dangerous situation. Thanks guys.