98 z5 auto stumbles when braking

[inferno94]

I'm trying to fix my moms car that my dad has "maintained" up untill now. Its got 75000km and recently failed an etest due to carbon build up but I beat it for a day then it passed. It's so full of sludge cause my dad doesn't believe in oil changes (except for his car). I've tried many products like seafoam and they make it better but it gets worse again eventually as the products never really clean it out.

Is there a way to clean this crud out when conventional methods fail without dissassmbly? Are there common causes of braking idle droop in these cars, I mean enough for the whole car to shudder and vibrate?

I'm also working on teaching my mom that mazda's like to rev and it's not crying when the engine whines its like what you do when you get a massage, she normally tries to not let it see 3000rpm. She was really pissed when she was initially told that she wrecked her car by driving like a 90 year old.

I took the head off my bpt and showed her how minty clean it is everywhere but she still thinks revving up to 5 or 6 thousand every once in a while will hurt her car (she is used to driving domestics).

[almighty4wd]

well, not to sound like an ass, or skirt the original question: but the problem isn't with the car, its the drivers. Your dad needs to be taught proper vehicle maintenance, and your mom needs a good lesson on how to drive a car to its potential without being aggressive.

anyways.
If it's got that much buildup at 75K......That's really low miles for an engine to be ****ting itself already. Really to clean it, your only option is to tear down, and clean it properly, seafoam won't get half of what really needs to leave.

Braking. Could be an issue with the tranny, the tq converter. One of the solenoids might not be kicking the motor down, the slowdown is dragging the motor to stumble. Injectors might need a good cleaning. Try the seafoam for the tank, or some injector cleaner.

[Beerizfood]

Hi
I am in Peterborough,hows ur snow fall lately?
Any way GM sells a combustion chamber treatment up here (may have it in the US I dont know) You can remove the plugs and let it soak overnight to clean rings and pistons etc on bottom end.It can also be entered through a vacuum port on the intake to clean the valves etc with engine running.
You must regulate its flow .I used to use it at the Mazda dealer with decent success.You would need two bottles .If you want to persure it let me know and I will give you detailed instructions.
Cheers
Beer

[Beerizfood]

OOPs ,and for the stumble you can try servicing and setting up the IAC valve.
EGR sticking can cause that too!
If the car almost dies when you press on the brake pedal at idle it is possible the brake booster is leaking vacuum but these cars are not known for that.
Any DTC's?

[inferno94]

well, not to sound like an ass, or skirt the original question: but the problem isn't with the car, its the drivers. Your dad needs to be taught proper vehicle maintenance, and your mom needs a good lesson on how to drive a car to its potential without being aggressive.

That's been an issue I've tried to solve for a while but I'm sure if I can prove my point by either fixing it or dissassmbing it my mom would drive it properly (my mother in-law to be has the same anti rpm disease). My dad just doiesnt like to do anything not even drive her car over to a place and get it changed, so I don't take offence.

The problem that made it not pass emmisions was the egr its self so I may take it off and clean it. It was getting full of carbon deposits as the engine rarely got fully warmed up (it doesn't help that my mom works 3 blocks from home and the grocery store is closer than that). It got soo bad it was backfiring at its worst.

I used to be a garage tech and this is why I'm stumped I've tried the products like Beerizfood mentioned with no success. There is no iat issue and no vacuum leaks. EGR sounds promising though.

[Beerizfood]

That's been an issue I've tried to solve for a while but I'm sure if I can prove my point by either fixing it or dissassmbing it my mom would drive it properly (my mother in-law to be has the same anti rpm disease). My dad just doiesnt like to do anything not even drive her car over to a place and get it changed, so I don't take offence.

The problem that made it not pass emmisions was the egr its self so I may take it off and clean it. It was getting full of carbon deposits as the engine rarely got fully warmed up (it doesn't help that my mom works 3 blocks from home and the grocery store is closer than that). It got soo bad it was backfiring at its worst.

I used to be a garage tech and this is why I'm stumped I've tried the products like Beerizfood mentioned with no success. There is no iat issue and no vacuum leaks. EGR sounds promising though.

I dont mean to sound condecending ,I dont know how much you guys know/dont know.