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Joshua Haynes
Joshua Haynes,
Category: Chevy
Satisfied Customers: 257
Experience:  Lead Technician/ Manager at Precision Tune Auto Care
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1989 Chevy K1500 350 tbi auto trans A/C and just did an engine

Customer Question

1989 Chevy K1500 350 tbi auto trans A/C and just did an engine swap with a motor from the same year vehicle. Running VERY rich at start up and have exhausted my knowledge on how to solve the problem. Replaced CTS with a new one. Checked yellow wire to CTS to verify current at 5.43 volts. Checked IAC yesterday and it appears to be good. Any suggestions?
JA: Sometimes things that you think will be really complicated end up being easy to fix with Chevy. The Chevy Mechanic I'm going to connect you with knows all the tricks and shortcuts. Are you hoping to fix this yourself?
Customer: Yes, I'd like to find the answer and take care of it ASAP so I can get my old work truck back on the road.
JA: Great! What have you tried so far?
Customer: Did you read my first post?
JA: Is there anything else the Chevy Mechanic should be aware of about your Chevy?
Customer: It was running perfectly fine just an old tired worn out engine. Replaced the engine and it's running VERY rich.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Chevy Mechanic about your situation and then connect you two.
Submitted: 7 months ago.
Category: Chevy
Expert:  Joshua Haynes replied 7 months ago.
Hi, My name is***** am going to try to help you figure out your rich condition. What is the evidence of it running rich?
Customer: replied 7 months ago.
Strong gas odor out the exhaust. Black spark plugs. Injectors dumping fuel. It will only start with wide open throttle.
Expert:  Joshua Haynes replied 7 months ago.
Well, I'd say that is rich! You mentioned that you replaced the cts and checked the IAC...did you use these components from the original engine?
Customer: replied 7 months ago.
New CTS! Tried 3 different IAC,s
Expert:  Joshua Haynes replied 7 months ago.
Yikes! Ok, I would call both of those ruled out. Have you checked for restricted exhaust flow?
Customer: replied 7 months ago.
Exhaust is not restricted
Customer: replied 7 months ago.
Truck was running fine before the eng swap
Expert:  Joshua Haynes replied 7 months ago.
Ok, was this a used engine, rebuilt engine or a crate engine?
Customer: replied 7 months ago.
Used/less than 40k miles after rebuild from one my other trucks that was wrecked.
Expert:  Joshua Haynes replied 7 months ago.
Thanks. So all the peripherals, intake, sensors and other components are from the original truck?
Expert:  Joshua Haynes replied 7 months ago.
Original meaning the current truck, sorry. What I'm trying to find out is if you took all the components off of the old engine and put them on the rebuilt engine or if some of the other parts are from the new engine
Customer: replied 7 months ago.
Yes. Swapped TBI off the old motor. No joy.
Expert:  Joshua Haynes replied 7 months ago.
Alright, thanks for that info. I am going to do a little bit of research on the fuel mapping strategy for this truck on All Data and try to form a theory on what is happening. Please bear with me for a few minutes.
Customer: replied 7 months ago.
Plus: got the ohm meter out and checked CTS and wiring appears to be good.
Expert:  Joshua Haynes replied 7 months ago.
Great, Thanks a lot.
Customer: replied 7 months ago.
Jumped A and B on the OBD1 connector and had code 15.
Expert:  Joshua Haynes replied 7 months ago.
That code is very helpful, thanks
Customer: replied 7 months ago.
Still don't understand why that code comes up with 3 different CTS and one of them new? And the wiring appears to check out?
Expert:  Joshua Haynes replied 7 months ago.
I'm not sure, but I bet that is the problem. We must be overlooking something. Have you tried jumpering the two pins on the connector to fool the computer into thinking it is warmed up?
Expert:  Joshua Haynes replied 7 months ago.
It sounds to me like somewhere in the harness for the sensor connector there is an open circuit. The lower the resistance the higher the temperature, the higher the resistance, the lower the temperature (as far as the computer reads it). So, if there is a break somewhere in the wire, it would cause the computer to think that the coolant temperature is negative 30 degrees. This would definitely cause a rich condition.
Customer: replied 7 months ago.
You mean unplugging the connector to the CTS and jumper info across them?
Expert:  Joshua Haynes replied 7 months ago.
Yes, exactly
Expert:  Joshua Haynes replied 7 months ago.
That code only sets if the computer reads a ridiculously low number from the sensor (-47 degrees) for more than 3 seconds. This is why I think the problem is in the wiring.
Customer: replied 7 months ago.
Wow! Didn't think about grounding it out. I thought that would send it to -40 degrees but what you saying is it sends it the hot side of the CTS?
Expert:  Joshua Haynes replied 7 months ago.
Exactly!
Expert:  Joshua Haynes replied 7 months ago.
Now, if my theory is correct, it will not work because the circuit is broken between the pcm and the connector for the sensor. I will also send the pcm pinout so that you can test it there as well. What you are going to do is the same thing that you do at the sensor, ground it out. Except, you are going to do it at the pcm connector.
Expert:  Joshua Haynes replied 7 months ago.
The two wires that go to the sensor are "C10" and "D2". You will jumper these two. I think that once you do, it will run correctly. Then, the only thing left to do is find where the wire is broken and/or just lay a new wire. Good luck buddy!
Customer: replied 7 months ago.
Again..... WOW. I'm slammed with work today and won't be able to get back to the truck until tomorrow. I'll ground the CTS plug and see what happens. If I'm still getting a code and VERY rich condition I'll start checking for a bad ground. I'm suspicious that if it's a bad ground it's the wire coming out of the harness on the motor that grounds to the thermostat housing?
Customer: replied 7 months ago.
Awesome! I bet you are on top of this Josh! I'm going to do exactly what you suggested and get back to you tomorrow. Have a great day! Mine is looking better.
Expert:  Joshua Haynes replied 7 months ago.
Man that is great to hear! I'm so happy your day is better just from that. Have a great day and I'll talk to you tomorrow!
Customer: replied 7 months ago.
Hey Josh, made sure ALL the grounds were good on CTS. now I'm getting a code 42 and I don't have that code on my sheet.
Expert:  Joshua Haynes replied 7 months ago.
Ok, let me look it up for you give me a few
Expert:  Joshua Haynes replied 7 months ago.
Did you jump the wires like we discussed?
Expert:  Joshua Haynes replied 7 months ago.
That code is in reference to electronic ignition timing
Customer: replied 7 months ago.
Not at the ECM. Put another ground wire on CTS and then code 42 showed up. Got the Internet to tell me it a timing code. Plugged the connector in that was unplugged to set the timing and no codes. Now I've pulled all the spark plugs to static time the engine ad start over checking timing.
Expert:  Joshua Haynes replied 7 months ago.
Do you mean that the timing connector was already unplugged?
Expert:  Joshua Haynes replied 7 months ago.
I'll send you a flow chart for that code
Expert:  Joshua Haynes replied 7 months ago.
CODE 42 - ELECTRONIC SPARK TIMING (EST)Circuit Description :
When the system is running on the Ignition Module, that is, no voltage on the by-pass line, the Ignition Module grounds the EST signal. The ECM expects to see no voltage on the EST line during this condition. If is sees a voltage, it sets Code 42 and will not go into the EST mode.When the rpm for EST is reached (about 400 rpm), and by-pass voltage applied, the EST should no longer be grounded in the ignition module so the EST voltage should be varying.If the by-pass line is open or grounded, the Ignition Module will not switch to EST mode so the EST voltage will be low and Code 42 will be set.If the EST line is grounded, the Ignition Module will switch to EST, but because the line is grounded there will be no EST signal. A Code 42 will be set.Code 42 sets if there is an open or a short to ground in the EST or by-pass circuit.Test Description : Numbers below refer to circled numbers on the diagnostic chart.
Code 42 means the ECM has seen an open or short to ground in the EST or bypass circuits. This test confirms Code 42 and that the fault causing the code is present.
Checks for a normal EST ground path through the ignition module. An EST CKT 423 shorted to ground will also read less than 500 ohms; however, this will be checked later.
As the test light voltage touches CKT 424, the module should switch causing the ohmmeter to "overrange" if the meter is in the 100-200 ohm position.
Selecting the 10-20,000 ohms position will indicate above 5000 ohms. The important thing is that the module "switched".The module did not switch and this step checks for:
EST CKT 423 shorted to ground.
Bypass CKT 424 open.
Faulty ignition module connection or module.
Confirms that Code 42 is a faulty ECM and not an intermittent in CKTs 423 or 424.
Diagnostic Aids :
The "Scan" tool does not have any ability to help diagnose a Code 42 problem. See Diagnosis By Symptoms - No Trouble Codes Stored.
Expert:  Joshua Haynes replied 7 months ago.
I'm working on my mobile...I can't attach charts from here but there is the circuit description. I hope it helped
Customer: replied 7 months ago.
Yes. All info is good! I'll get back to you when 100% on the timing and eliminate that ?
Expert:  Joshua Haynes replied 7 months ago.
Sure that sounds like a plan
Expert:  Joshua Haynes replied 7 months ago.
Hello my friend! I hope you're doing well. I am just checking in
Customer: replied 7 months ago.
Doing well as a matter of fact. Had to bail on the truck not long after our last text due to leaving the shop for a trip to the job site. Back on the truck early in the morning and without interruptions hopefully. lol
Anyway, after jumping an extra wire to the CTS and plugging the advance back in...... No codes! In trying to static time the motor I had "0" compression on #1 and really got worried. Turns out it was just a stuck lifter from sitting too long in the wrecked truck. A smack with a big hammer took care of that and I got the call to be on the job site. So naw I can static time it and move on from there. My wife was in the shop with me today and her version of the problems that led up to finding the stuck lifter was God didn't want me to finish it and find out on a test drive I had a dead cylinder. I had to agree with her. So tomorrow I will get it timed and hopefully ready for the job site by Monday. Talk to you tomorrow!
Expert:  Joshua Haynes replied 7 months ago.
Awesome! I hope you have good luck
Customer: replied 7 months ago.
It's running as it should!!! Just need to finish buttoning everything up!!! Thank you for ALL your help Josh!
Expert:  Joshua Haynes replied 7 months ago.
That is fantastic news! I am glad you got it figured out and it has been a pleasure serving you! Have a great day
Expert:  Joshua Haynes replied 7 months ago.
I forgot to mention, I would love a positive rating!

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