Truck started acting weird yesterday. After about 20 minutes of driving, it started to sputter at about 55 mph. But the weird thing is, that it only does it in OD. when i downshift into 3rd, it runs fine? Also when it started, I noticed the temp gauge was way loser than usual. It was reading around 130 degrees, and it normally runs right under the 210 mark. It threw codes 32(EGR) and 43(Knock Sensor). I took the EGR off a few days ago and cleaned it and assured it was working properly. Any ideas? 89 350 TBI, 700r4 transmission. has new fuel pump and all new gaskets on TBI. Any help will be greatly appreciated! Thanks in advance! Aaron.
CK5
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1989 c1500 question!
- Thread starter Aaron1989
- Start date
Stomis
Professional Amateur
Based on what you're saying it sounds like the computer is pulling timing due to knock when the EGR begins to open. Its only doing it in OD because thats a required condition for the EGR to come on. I would disconnect the egr completely so it does not open and take it for a drive. Perhaps the EGR is clean but it function by a vacuum bell controlled with a vacuum switch doesnt it? Maybe the bell is leaking causing you to go lean on fuel at the same time the EGR is deliberately causing the lean cruise making it WAY to lean hence the knock and pulling the timing.
After reading you're comment, I remembered I had a Delphi EGR that I bought for my old 90 K5 a few months back and never put it on. Replaced it and so far so good. I only drove it a couple of miles, so I'm not entirely sure yet but hopefully that'll fix it. By the way, I love your 94 build. It's actually what inspired me to buy this truck. After reading your thread, I'm planning on starting my 5.3/4L60E swap around the first of the year. Great thread with lots of useful information! I hope to see it "finished" soon!
Well It is still doing it. But after further investigation, it may not be anything related to the engine. The "sputtering" i mentioned actually feels like the transmission is shifting in and out of OD. I am pretty much clueless when it comes to transmissions. But when the truck gets to operating temperature, it starts doing it. it shifts fine and stays in OD when truck is cool. once it reaches around 180-190 is when it starts. Maybe the converter is going in and out of "lockup"? Im going to disconnect the lockup connector on the tranny tomorrow to see if that does anything. But is there any insight that you guys could give? Does it sound like this might be causing my issue? anything i should check for?
Stomis
Professional Amateur
Gear hunting is really bad for the transmission. It could also be the lockup like you said. Start where you said and disconnect the lockup. Im no a slushbox guy as you know so Im really no help there...
Good luck and thanks for the kind words on the build. Update coming right now actually.
Good luck and thanks for the kind words on the build. Update coming right now actually.
Well turns out it is the lockup. I didnt disconnect the clip. but i did do the brake trick. i waited until the truck started acting up and i lightly pressed the brake which unlocks the TC and it acted fine. so my question is. Is the lockup controlled by a switch? is it a vacuum or electrical switch? and is there anything else that could cause this?
DirtRidinz71
1/2 ton status
Check out the Coolant temp sensor (one on the intake). I had a similar problem which was caused by a wiring short at the cts.
The TC will not lockup until the truck reaches a certain temp.
The TC will not lockup until the truck reaches a certain temp.
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would the cts cause it to lock and unlock repeatedly? Or just not come on at all? Because mine is locking but it is locking and unlocking repeatedly.
DirtRidinz71
1/2 ton status
Mine would lock and unlock at random when it was shorting out/losing connection.
So what could cause the TC to lock and unlock repeatedly? is there a vacuum switch? Ive been doing research but havent found anything yet. Would the TCC solenoid have anything to do with it? I dont want to drive it until it is fixed and need to get it back on the road soon. so any help is greatly appreciated!
Stomis
Professional Amateur
With TBI/TPI the computer controls the lockup. A malfunctioning sensor could absolutely do it if something is coming in and out of range of lock up do to malfunction.
Thanks! I guess i will start with the TCC solenoid and go from there!
