Issue with hesitation on cold start

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Topic author
Theodore
Posts: 53
Joined: Tue Sep 04, 2018 5:26 pm

Issue with hesitation on cold start

Post by Theodore » Sat Aug 03, 2019 7:42 am

Am looking for some advice. After last weekend’s adventure replacing spark plugs & assorted EFI sensors (IAC, TPS, MAP), + we’ve now got a nice running car, with the exception of acceleration just after a cold start. Have been daily driving the Wagoneer all week, and every day, 3X/day (morning, lunch, & evening) I see the issue, where the car starts, and until the temperature gauge reads above 100 or so, there’s severe hesitation, and often dies pulling out from parking spots and/or red lights/stop signs.

We’re running Affordable Fuel Injection’s EFI setup. Had myself talked into EGR valve issues – that is, til I went out today to discover there’s one there, but there’s no vacuum lines attached, and there’s no EGR/CTO switch to activate it either. This morning, I took it off to check that it could hold vacuum – that’s good; and it was closed – also good, given no vacuum line were connected.

So, I’m wondering whether to attempt to put the EGR/CTO switch & vacuum lines back? Or, do I get a EGR delete plate to block the port? Given parts & lines are missing, I’m wondering what else is missing to get back to scratch.

If it’s not the EGR, what else could cause a severe hesitation at cold start?

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babywag
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Re: Issue with hesitation on cold start

Post by babywag » Sat Aug 03, 2019 9:16 am

best way to diagnose is datalog or scantool to monitor what the sensors are reading/ecm is doing during the problem.

without seeing data any advice is just a guess.

The coolant temp sensors are sometimes bad which results in improper fueling due to incorrect engine temp being reported.
since it is only on cold starts that would be the first suspect.
a datalog or even testing it with an ohm meter will tell you if it is bad.

pretty unusual to need iac/tps/map all @same time, and with shotty quality of aftermarket stuff a big roll of dice.
best to diagnose and replace single sensor @ a time vs. throwing multiple parts.
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.
email me I never receive PM notifications and frequently do NOT see them.


Topic author
Theodore
Posts: 53
Joined: Tue Sep 04, 2018 5:26 pm

Re: Issue with hesitation on cold start

Post by Theodore » Sat Aug 03, 2019 1:27 pm

Was thinking obd1 didnt provide much of a datalog capability; everything ive seen so far talked about jumping ALDL pins & counting blips of the check engine light. Given the running state of the car, have gotten to the point that i dont trust previous work. The good news is: other than this issue, running-wise, ive been able to clean running issues up.

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babywag
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Location: Land of Fruit Loops & Coconuts

Re: Issue with hesitation on cold start

Post by babywag » Sun Aug 04, 2019 9:43 am

with a cheap usb setup and tunerpro on a laptop can datalog easily. burning a new chip(tuning) requires a chip burner.
can even buy bluetooth aldl and scan/datalog with an android phone these systems.

tons of info online about gm tbi conversions/tuning/etc.

the gm stuff has been around for decades and very well supported.

poor man's digital dash...(can datalog too)
Old phone + cheapy usb board + ALDLDroid

Image
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.
email me I never receive PM notifications and frequently do NOT see them.


Topic author
Theodore
Posts: 53
Joined: Tue Sep 04, 2018 5:26 pm

Re: Issue with hesitation on cold start

Post by Theodore » Sun Aug 04, 2019 6:27 pm

Thanks, babywag. I appreciate it. Had never heard of any of that. Will take a look.


Topic author
Theodore
Posts: 53
Joined: Tue Sep 04, 2018 5:26 pm

Re: Issue with hesitation on cold start

Post by Theodore » Tue Aug 06, 2019 3:38 am

Have been reading about ALDLdroid, TunerPro, etc, after looking at the ALDL port on the Wagoneer - there’s only 3 wires running to it (Ground, Diagnostic, & Check Engine Light)- Is it safe to assume that all It can do show codes via blinking the check engine light? Such that data logging, etc is not possible with this setup as it sits?

Image


Found on obd-codes.com:
Image

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babywag
Posts: 1147
Joined: Fri Jun 08, 2012 7:29 pm
Location: Land of Fruit Loops & Coconuts

Re: Issue with hesitation on cold start

Post by babywag » Wed Aug 07, 2019 7:01 am

That's the later 8192 baud odbi plug diagram.

You should have the earlier 160 baud version.

All that is needed it 2 wires to datalog and a typical aftermarket gm tbi uses 3 wires.
A cheap usb->ttl converter board + usb cable or a more expensive aldl cable or bluetooth adapter is needed.
-Tony
'88 GW (aka Babywag) '90 GW (aka JunkBucket) both fuel injected.
email me I never receive PM notifications and frequently do NOT see them.


Topic author
Theodore
Posts: 53
Joined: Tue Sep 04, 2018 5:26 pm

Re: Issue with hesitation on cold start

Post by Theodore » Fri Aug 23, 2019 6:41 am

Thanks for the advice. The 1320electronics Bluetooth ALDL setup is next on my list.

Also, a few days ago, I spoke with AFI & given the distributor I have is mechanical & not computer controlled, it was recommended that I reset initial timing to between 5&10 degrees advanced, and see how it works & go from there. I’ve not had a chance to get that done yet - have been tied up with the spring/shock/tire swap.

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