The Stupid Engine Questions Thread

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

jeff1953

OBS Enthusiast
Joined
Apr 18, 2017
Messages
59
Reaction score
8
Location
southeast Ks.
Put the o2 sensor in but have not drove, my other problem is the ESC and I replaced it not to long ago because it set a code and it still sets a code after putting a new one in. got any ideas on that, and thank you.
 

PlayingWithTBI

2022 Truck of the Year
Supporting Member
Joined
Jan 3, 2019
Messages
9,552
Reaction score
14,679
Location
Tonopah, AZ

haroldwca

Newbie
Joined
Jan 25, 2020
Messages
36
Reaction score
41
Location
Southeastern NC
My truck like to randomly idle very high while in gear (not in neutral) and hard shift 1-2 gear with 700r4 (4l60 non-e). However, most of the time its fine and runs smooth as silk. I've recently replaced the tbi gasket, fuel pump, and tps. I've gone through all of the vacuum lines and replaced any that seemed suspect. I'm not sure where I should be looking anymore. Any tips?
Inside a 700R4, the 1-2 accumulator is a piston that, under increasing fluid pressure, compresses a spring inside a chamber. This controls the firmness of the 1-2 shift. Due to age, the piston often breaks off the center shaft and tilts off-center. The somewhat stuck piston causes the fluid pressure to build to a much higher level (and delay the shift) before it gives way and allows the shift to occur suddenly (to say, hard).

The transmission does not have to be removed to check this piston. With the transmission pan and filter removed, the round cover with three bolts attaching it to the case in one corner is the 1-2 accumulator. With the accumulator removed, check to see if the piston compresses freely into the chamber without tilting and binding. Any such restriction of free movement indicates replacement of the piston is required. They are not expensive, but a parts store may have to order it as opposed to having it in stock.

Be advised that there are one or two check balls that come out when the accumulator housing is removed. You will want to verify the location of these check balls before reassembly. Use transmission assembly gel to hold the check balls in place during assembly (they will not defy gravity and stay in place without the assembly gel).

If you're itching to see what's inside an automatic transmission, this is a first step in the journey, and again, this procedure does not require removing the transmission. Good luck !
 

Thirsty

Newbie
Joined
Oct 22, 2020
Messages
20
Reaction score
23
Location
Canada
What oil do I run in my 2000 ccsb 7.4. It has 220kms and I’m in Canada so it gets -40c here
 

Erik the Awful

Supporting Member
Supporting Member
Joined
Aug 9, 2019
Messages
7,616
Reaction score
15,528
Location
Choctaw, OK
I'm a fan of 10w30 in older engines, but I'm in Oklahoma. I'd guess 5w20 would be suitable for you.
 

SUBURBAN5

I'm Awesome
Joined
Jul 18, 2020
Messages
4,674
Reaction score
7,945
Location
Houston
If I got the mpfi injectors. What's the lowest psi the truck will run?. Right now I'm at 50psi at idle and just curious if it gets lower will it misfire or die completely?
 

James_J

Newbie
Joined
Oct 24, 2020
Messages
1
Reaction score
0
Location
Jacksonville Beach, FL
Got a 1994 305 TBI that will start, but won’t run. You have to feather the throttle to keep it running. I have replaced the MAP Sensor, TPS, and the Idle Air Control valve. If i disconnect the vacuum line from the MAP sensor, and plug it, I can get the engine to run normal for a short moment of time. To keep it running, I have to give it a little bit of throttle. Anybody have an idea of where I should start trouble shooting next?
 

PlayingWithTBI

2022 Truck of the Year
Supporting Member
Joined
Jan 3, 2019
Messages
9,552
Reaction score
14,679
Location
Tonopah, AZ
Anybody have an idea of where I should start trouble shooting next?
1st thing I'd check is your fuel pressure, it s/b 9 - 13PSI per GM specs but, if it's lower than 10 you'll have issues. Then get a scan tool and see what's going on.
 
Top