When it's cold it starts easily. When I shift to P or N or R or D the engine works. The rpm decreases almost to 500-600 at the first 1-2 seconds of shifting to D or R and then it increases to 700-800.

But when the engine is hot it works properly on P and N
And when I shift to D or R the engine fails. And it's hard to start it when it's hot.
What can it be?

 

Ttt

 

What do you mean by "fails"? Do you mean it stalls? Is the service engine soon light on?

 

I'd start with the engine codes but it does kinda sound like what happened with mine when I spun two bearings and I didn't have any SES codes for it. Depending on how fresh the oil is, try draining the oil and check for any metal shavings. If there's no shavings and it's fairly fresh oil, you can always just pour it right back in. From what I understand, when the oil is cold it is thick enough that it allows everything to run but when the engine warms up and the oil thins out if you have spun bearings or such the thinned out oil causes the bearings to wear even more and cause the engine failure/stalling. Especially if the knock sensors are detecting knocks and puts the retard so high, it'll stall out on you. I was data logging as I drove around the block with my spun bearings and if I so much as let my foot off the gas it'd die and it was from the knock sensor going crazy and the knock retard skyrocketing up to the point that it'd stall - never had any SES codes though.

I hate to jump to the worst possible thing but hey if it's not that then whatever it is can't be as bad, right?

 

Yeah, I ment stalls

 

You forgot to answer my third question.

 

I made computer diagnostic. It showed only a bad oxygen sensor. I changed it.
I though the car stalled because of it. The fuel formula was too rich. Too much fuel and too little air. The catalytisator became red. I could smell the fuel from the exaust.
But the problem was not in it.

The oil is terrible in the engine. It's not clear. And very old. I found the car in someone's yard. The car stood there for 7(!!!) years and nobody rode it. Nobody even start the engine for 7 years.
And now I repair it.
I managed to start the engine.
I do not ride the car yet, so I decided to change the oil later a little bit. By the way the oil pressure is about 2.5 bar at 800rpm.
I want to believe that the reason of stalling is bad oil. I think it's time to change it.

Well, meissenation, it can be lots of things which made the engine stop in my situation, I think.
They are:
1. Bad compression.
2. Bad fuel pump
3. Bad fuel filter
Maybe smth. else, I don't know...

I checked the compression in cold engine. It was 12 bar in every cylinder. Only in 1st it was 9.5
But I can't check it in hot engine. I think you undestand why

 

Oh, sorry ACE1252.
The service engine soon light is on only when I switch the ignition on. And when I start the engine it goes out

 

2.5 bar@800rpm is around 36 psi. That's a little high for idle. In an unmodified LT1 it's normally around 20 psi. However it could be high due to that seven year oil.....LOL!

For your compression.....12 bar is around 174 psi. I think that is okay, but the other one....137 psi. That worries me some. Just for comparison, most of mine cold were over 200 psi, with the lowest around 195 psi. However, mine has not sit for seven years either.

I'm sure the oil needs changing after seven years, but I'm not sure how that could be connected to the stalling or hard starting.

Check your fuel pressure...what is it when primed(with the key turned to on and not running) and at idle? I think you maybe on to the problem with suggesting fuel issues. You may also have plug issues. If the cat is getting red, it has to be dumping raw fuel into the exhaust.

If I was dealing with something that sit for that long, I would change all the plugs, fuel filter, drain the gas tank, fuel lines, and change the oil.

 

Well, I can't understand it too.
What should I do, what do you think?

 

Well, get the old fluids out of it and put in new oil, gas, gas filter, oil filter, trans fluid and trans filter. Coolant wouldn't be a bad idea to change either....but you maybe able to wait on that.....

After that, change(or at least check) the plugs.

Next, check the fuel pressure. Let's see if it is normal. You need to get a reading when primed, at idle, and at idle with the vacuum line pulled off the back of the fuel pressure regulator. The readings should be(approximately) 43 psi, 38 psi, and 43 psi respectively.

 

Of course I will change everything.
The cat was red earlier.
I changed spark plugs(AC Delco 41-943) And oxygen sensor(AC Delco AFS 75)
Now I dont smell raw fuel from exhaust.
I think the cat is no longer red now. I'll check.

I think it would be difficult to drain and clean fuel system.

 

If I'm not mistaken, there is a way to manually turn on the fuel pump. There is a wire on the passenger's side under the hood that you can put 12 volts on(I think....if not that then ground...hmmm may need to make sure) and it will run the fuel pump. You could disconnect the fuel lines(from the injector rail) and drain it like that. I will try to find the picture of that wire on Shoebox's site.

Edit: Here is that picture....

 

I'll try to find some information in my service manuals on why the thing may stall in R or D....it could be some type of transmission issue. Which, if it is, I will have to defer to someone else....I have only a basic understanding of an automatic transmission.

 

ok, thnx