Hi Scotty, thanks so much for your informative videos and your energetic style!

I have a 4.7L Limited 2008 Grand Cherokee with around 200,000 Km on it. It used to work like a charm. Once, I forgat to fill the radiator full for some months and the engine went down. I got the engine repaired in a dealership, a valve, and full set of gaskets where replaced. Now it works, has no check light on or any code in any scanner. It works normally until it's cold, once the temperature becomes like normal it loses power dramatically, say 0-100 km/h in around 20 seconds or more, while it used to be around 8 sec before the desastre!
When it's warm if I hold the acceleration pedal the RMP goes near 4500 or 5000 before the gear changes from 1 to 2-3-4. But when it's around 3000RMP if I release the pedal a little bit it changes the gear normally. When the speed riches around 100km the engine works normally again to +170km/h until I lower the speed and I need to accelerate again which is extremely annoyingly powerless again.
Good to mention that the fuel economy has dropped significantly too; like 30%!

When the engine is cold it starts well like before, when it becomes warm, although it starts at the first try, it seems like having some difficulties to turn the engine on.

The injectors have been washed professionally, 16 new spark plugs, new PCV valve, new full synthetic oil...

So, to summeriz: The engine works great until it becomes normally warm, then it loses the power until you rich like 100km/h.

Right now I live in South America, otherwise it would be a good idea to you check the car in person. So far 3 different mechanic have checked the SUV, but none was able to resolve the problem.

I wonder if you could localize the problem.

Thank you so much in advance.

Best regards
Pooria

Comments
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PooriaSh
PooriaSh

Just remembered to mention that the transmission runs silently and smoothly while I put it in neutral while driving.

PooriaSh
PooriaSh

HI Scotty, thank you for your rapid reply.
Today I got the transmission checked again in the dealership. It seems fine. The thing that makes me not thinking about the transmission is that when the engine becomes warm, the SUV has some minor difficulty to start. As I already mentioned it turns on the first try, but doesn't sound like when it'sead cold.
The transmission fluid seems OK too, pinkish almost. Another thing to have in observation is that this problem came across just after the engine repair, before the repair the car was running just excelente.

ScottyKilmer
ScottyKilmer

Editor

first, have a pro check the transmission out, that shifting when letting off the gas is generally a sign of a failing transmission.