No throttle response when cold momentary - TerrainForum.net: GMC Terrain Forum
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post #1 of 5 (permalink) Old 12-02-2019, 04:19 PM Thread Starter
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No throttle response when cold momentary

My 2014 Terrain with 145K miles has recently started to have an issue with throttle controls right after startup. I've owned this since new.

When cold it revs fine for 30 seconds then gets really rough and then becomes fine.
If I don't have time to wait and start driving the engine losses responsiveness / no throttle control for 2-4 seconds, then runs fine.
If running really slow verge of stalling but has only stalled once.

Did recently replace the exhaust manifold (cracked), cat (P0420 code after manifold), upstream 02 sensor, and resonator box (had a nice hole) (thank you northeast winters). I can't tell if this is a fuel pressure issue or o2 sensor issue / how would i run that test.

Just replaced the spark plugs and that seemed not to help.

Seeing if anyone has seen this before.
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post #2 of 5 (permalink) Old 12-03-2019, 12:52 AM
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Quote:
Originally Posted by btg3318 View Post
My 2014 Terrain with 145K miles has recently started to have an issue with throttle controls right after startup. I've owned this since new.

When cold it revs fine for 30 seconds then gets really rough and then becomes fine.
If I don't have time to wait and start driving the engine losses responsiveness / no throttle control for 2-4 seconds, then runs fine.
If running really slow verge of stalling but has only stalled once.

Did recently replace the exhaust manifold (cracked), cat (P0420 code after manifold), upstream 02 sensor, and resonator box (had a nice hole) (thank you northeast winters). I can't tell if this is a fuel pressure issue or o2 sensor issue / how would i run that test.

Just replaced the spark plugs and that seemed not to help.

Seeing if anyone has seen this before.
Mine does the same when it is cold. It idles at about 1250 rpm for about 15 - 30 seconds while in open loop and using the ECM stored fuel settings. Once it goes into closed loop, and the O2 sensors start to manage the fuel control it will go lean (slightly rough idle) to correct the rich ratio, and then settle back to a normal fuel control. I always let it warm up and go into closed loop (active fuel control) before driving. It also acts a little sluggish if I try to drive when the open/closed loop transitions. I would take a minute or so and let it warm up before driving. Much better than the old carburetor with heat/vacuum controlled choked cars that needed to run for 5 minutes before driving.
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post #3 of 5 (permalink) Old 12-08-2019, 07:42 PM
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I have same random issue, 2014 Terrain 2.4 awd. Only had the Terrain for 3,000 miles so far. When I bought it had bad 02 code, when I replaced the rear 02, code went away. At same time I replaced the (2) vvt sensors just as a preventive measure, cleaned the throttle body, cleaned the maf sensor and put new air filter in, also put a gm vented oil cap for extra piece of mind. Also ran some good fuel system cleaner My Terrain doesn't use any oil other than what's normal for a di engine, pcv line was oil free(I expected to see some, but none was there or in that area on top of engine that collects moisture and oil, was zero there) , not 1 drip. Doesn't stall, but for instance, last night went 60 miles, stopped at 7-11, got back in, was basically at idle with foot off gas when I started to move, sputter sputter sputter, gave it some gas, all was fine. Seems to do it more when at freezing Temps outside. Last night was like 45, so not freezing and engine was not cold since I just had driven 60 miles. Wondering if the AC coming on with defrost is causing idle to hickup or Was thinking maybe replacing iat/maf, not sure.

2014 Terrain SLE-2, awd 2.4.

Last edited by Rotwiler; 12-08-2019 at 07:45 PM.
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post #4 of 5 (permalink) Old 12-10-2019, 05:14 PM
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Respectfully Btg3318,
My 2 cents...
As part of the diagnostic journey.....
could you answer the following questions?


How old is your battery? If more then 3 years it should be checked!
Your air filter is new or clean? Is the air filter, and air box and throttle body clamps properly attached, that is no air leaks.

Have you cleaned your mass airflow sensor? What does your scan tool tell you about your mass air flow rate ? Is it around 0.40 lb/min at idle?

Throttle body has been cleaned?
Do you use top tier gas, and do you clean fuel injectors with Techron fuel system cleaner ( it has PEA) before each
oil change.?

What does your scan tool tell you about your short term and long term fuel trims? Are you hovering around zero percent? Or are you positive showing an air leak?

What does it tell you about your oxygen sensor voltages? Are they fluctuating between zero and 1 volts once the car has warmed up?

What is your engine temperature after it has warmed up? 180 degrees F?

D you have any misfires? How many and on what cylinder in the last 10 driving cycles?

What about your evap purge valve ...which lets fumes from your gas tank be consumed in engine.
How full or empty was your gas tank during your stalling engine event?

does your scan tool tell you your evap system values are in the correct ranges?
How about your purge flow monitor,, are they in the correct ranges?
(( I use the $80 on amazon, obdlink mx+ , scan tool, that pairs with iPhone)

My GUESS is....
canister purge solenoid — also referred to as an EVAP canister valve is stuck in the open position ....
My guess.... Who knows?

From the web .. ==>
The canister purge solenoid
— also referred to as an EVAP canister valve
— is responsible for “purging” the EVAP system by acting as the switch that allows the vapor into the engine.

Usually, a bad purge solenoid will display any of the following symptoms that can alert the driver of a potential problem in need of servicing.
1. Rough Idle
One of the first symptoms that a faulty canister purge valve may produce is a rough idle. In this case, you will notice the car running inconsistently while stopped or driving at low speeds.
If the canister purge valve fails and sticks open,
it will create a vacuum leak that can affect the engine idle speed and quality. A vacuum leak can also be caused by a broken or damaged purge solenoid or any of the hoses attached to it. It needs to be addressed as soon as possible, as it could lead to your engine stalling completely.

2. Poor Engine Performance
On top of a rough idle, a vehicle with a failing EVAP canister purge valve will display signs of poor engine performance. The engine may feel like its running “weak” and won’t generate sufficient power for acceleration.
Accelerating will feel like you’re pressing the pedal down and moving slower. The disrupted combustion process caused by the failing purge solenoid will lead to slow acceleration that needs to be addressed for repairs right away.

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post #5 of 5 (permalink) Old 01-13-2020, 07:28 AM
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Good information and people should read what you said. I replaced air filter, fixed 02 cel light with new 02 sensor, vvt solenoids replaced, same odd random idle. I noticed it's worse when under 40 degrees outside. I bought the new throttle body and maf, just because and nice to have a backup on hand. Pea fuel system cleaner is great recommendation, is the only type that actually helps modern vehicles. I put a double dose of techron in the terrain, but need to use tank up to see a difference. Is good deal on Amazon, like $9.00 for 32 oz bottle. Supposed to get snow this week almost every day, so I am waiting until snow is done to replace tb and maf. If those don't help, will test battery and try the gas tank purge. My fuel trims look good since I replaced the 02 sensor. I never use eco mode and try to remember to turn off defrost until the terrain is warmed up. If all that fails to correct issue, will replace plugs, easy and cheap. If all that doesn't fix issue .. Then I'm kinda stuck on what to do next. Never stalls driving, just after initial start and if I put the terrain in reverse, might or might not drop idle rpm, then runs fine, if i give it gas when in reverse it never stalls. Never had any check engine light except rear 02 and I know why that was setting a cel, my Terrain was hit in rear, moved exhaust some and they replaced the 02 sensor with wrong one and was bigger/ touching frame of the terrain. I bought this Terrain about 4,500 miles ago for $7,000 due to the previous accident, but all was repaired before I bought it. For a winter vehicle with awd was a great deal and other than the random rough idle, is near perfect, even smells like new vehicle inside, even with 57,000 miles.

2014 Terrain SLE-2, awd 2.4.

Last edited by Rotwiler; 01-13-2020 at 07:31 AM.
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