: 1999 Escalade jerks and shudders on highway. Answer



Freeflyer
12-10-12, 10:59 PM
I felt it necessary to post this. 1999 Escalade with 5.7L Vortec with multi port injection.
My 99 Escalade while driving down the highway would randomly jerk and shudder. Almost like it was loosing spark or fuel. No codes in the computer.
I troubleshot this for over a month. After replacing the fuel filter, fuel pump, distributor cap, spark plug wires, coil and ICM module. I had my android phone on with the Torque app and saw my coolant temp jumping all over the place anywhere from 70 degrees up to 185 and back again, this was NOT seen on the coolant temp gauge on the dash.
I changed the $8 coolant temp sensor and my truck runs like a dream.
Apparently when the coolant temp goes low the fuel injection dumps more fuel and chokes the engine. I am assuming.

I hope that one day this may help someone troubleshoot their truck.

the cadillac man
12-10-12, 11:10 PM
I felt it necessary to post this. 1999 Escalade with 5.7L Vortec with multi port injection.
My 99 Escalade while driving down the highway would randomly jerk and shudder. Almost like it was loosing spark or fuel. No codes in the computer.
I troubleshot this for over a month. After replacing the fuel filter, fuel pump, distributor cap, spark plug wires, coil and ICM module. I had my android phone on with the Torque app and saw my coolant temp jumping all over the place anywhere from 70 degrees up to 185 and back again, this was NOT seen on the coolant temp gauge on the dash.
I changed the $8 coolant temp sensor and my truck runs like a dream.
Apparently when the coolant temp goes low the fuel injection dumps more fuel and chokes the engine. I am assuming.

I hope that one day this may help someone troubleshoot their truck.

Man that's crazy how it did that but a rich engine runs cooler
Also I suggest having your cluster looked at as the temp gauge should respond to the temp sensors reading

Black88GTA
12-11-12, 01:17 AM
Man that's crazy how it did that but a rich engine runs cooler
Also I suggest having your cluster looked at as the temp gauge should respond to the temp sensors reading

Usually there are separate coolant temp sensors. One for the gauge, another for the ECU. Coolant temp sensors acting up can manifest in all sorts of weird symptoms you wouldn't think to associate with it.

the cadillac man
12-11-12, 01:48 AM
Usually there are separate coolant temp sensors. One for the gauge, another for the ECU. Coolant temp sensors acting up can manifest in all sorts of weird symptoms you wouldn't think to associate with it.

Ahh that's good to know(I never knew that there was two I guess I need to take a closer look at the engine wiring diagrams I have)
But it is true when any sensor acts up it can cause a ripple effect
Heck I think there is a temp sensor for the battery charging to deliver proper voltage
It shows one in the wiring diagrams yet I haven't seen one(might be hidden)