2003 Nissan Xterra stallls when i brake hard

8 months ago i had a blown head gasket and went with a total new engine replacement. I did not use my usual mechanic but another repair shop that had a good reputation due to the price of a the new engine. My car ran well for about 2 months then i started to notice 2 issues. 1) when i applied the brakes hard the car stalled on me and 2) when i put the car in drive there was about a second hesitation before the car would drive. The hesitation (slipping) only does it when the car is in drive gear (auto transmission) and after a few moments of the car runs well even when i park it and restart it the rest of the day. It only hesitates that way the first time i drive it for the day or if it has been parked for around 4 hours or more. The stalling when i press the brakes hard is constant. I took the car back to the repair shop and they told me my 6 month warranty did not cover that issue cause it was not a engine problem; they said they can look at the car but to even look at it was another $150. I think they are wrong and trying to get more $ out of me so I declined and now my 6 month warranty is expired and i still have the issue. When the car is in idle the rpms are very normal and when driving the rpms are normal. Any idea what it could be?

Bad diaphragm in the power brake booster? Just a wild guess, I am sure others will chime in.

The engine warranty would not cover this problem. Most places have a charge for diagnostic services, usually dropped if they do the repair. And its BRAKES not breaks.

Would a bad power brake booster also cause the hesitation when the car is in drive? seems to me the 2 issues are related and i did not have these issues before i had the engine replaced. The only issue i had then was a blown head gasket

... when i applied the brakes hard the car stalled on me...

Do you have to be moving to have this happen?

Do i have to be moving? Yes every time it has happened i was driving and having to come to a fast stop. If i am in park and depress the brakes had it does not stall

Yes every time it has happened i was driving and having to come to a fast stop. If i am in park and depress the brakes had it does not stall

Sounds like it’s related to the engine moving during the hard stop. Look for cracks or looseness in the air intake pipe from the air cleaner to the throttle body. Also, with it idling, wiggle all the wires and tubes around the engine you can safely get your hand on.

Try coming to a hard stop after putting the in neutral, could be trans need fluid and filter service or torque converter if it does not happen while in netral,

thanks for the comments. I will check all the above

The hesitation seems like a transmission problem. Unrelated to the engine swap. Check the tranny fluid level. If it is time, based on the routine maintenance schedule, have a proper transmission service done. If that doesn’t fix it, your next stop will probably be a transmission shop, either for a repair or rebuild.

The engine stalling when applying the brakes for a hard, that could be a transmission problem too. But my first guess would be that some wire or another is getting pinched or a connector stretched and coming disconnected briefly. Think about what happens when you stop hard. The back of the car rises and the front drops, and quite a bit. So everything is out of kilter for a few seconds, and wires can get pinched and stretched. The other thing that happens is the fluids rush toward the front of the car, so that’s another possibility, the engine might being starved of gasoline somehow is the first thing I’d suspect.

Thanks everyone who responded, it was the transmission fluid. It was very low, I added the fluid, had my regular mechanic check for leaks and there were none and car runs great once again. Thank you

Thanks for posting the result. Glad you got the problem fixed :smile: