Throttle delay stumble?

Tiny
SUKCHB
  • MEMBER
  • 1988 CHEVROLET 1500
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 124,000 MILES
I changed the egr valve and MAP sensor in my truck. When I hook up the vacuum lines properly, there is a huge throttle delay at low revolutions and the check engine light appear. It idles perfectly and drives perfect when cold for the first minute. When I take the vacuum line off the egr valve and just let it hang free, it works perfectly.
Tuesday, June 10th, 2025 AT 6:53 AM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,603 POSTS
Yep, the EGR valve is opening to early. I would replace the EGR vacuum controller which is located at the intake manifold near the distributor. If you cannot find one you might try Ebay or get a vacuum delay valve from Amazon or the parts store. Check out the images (below). Please let us know what happens.
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Tuesday, June 10th, 2025 AT 6:08 PM

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