njamal

1993 LS400 with 130,000 miles. It was running smooth without any rough idle or
acceleration hesitation. I had no problems or issues with this car. Then, I noticed some coolant underneath the car.
Found the hose, shown in the picture, leaking. However, car was not running hotter or
displaying any other symptoms. Ordered the part ($17.00), took 2 days. So, drove car for next 2 days adding Coolant when necessary.
Received the part and replaced the part and the clamps. In the process,
I may have rotated the ****, shown in the picture, a bit. But, overall the repair
went smooth and the leak is gone. But, right afterwards car is now idling rough
going from 500 ~ 1100 on its own. Shakes/Vibrates violently and accelerates
hesitantly. Have not stalled yet.

I have removed the ECU (inside the cabin), EFI (under the hood) fuses and battery terminal (lost all memory settings) for more than 2 hours. Did not see any improvement in idle and/or acceleration problem. The car really shakes violently at times like it is having problem breathing...

What have I done while replacing the hose that has caused this? Was it that ****?
Or did the coolant leak end up damaging something else?

I do not want to go to the dealer, yet, and play along with their process of elimination
diagnostic techniques. I know they would say change spark plugs, wires,
clean fuel injection, throttle body, replace TPS, etc. Don't have that kind of money.

What I want to know is, what possibly has gone wrong? What will it take to fix
so that my car runs like it was before this stupid hose replacement?

Any ideas and/or prior experiences will be helpful and appreciated. Also, any
repair shops that are reasonable in Houston area that I can trust?

Thanks.

persian451

i beleive that **** is the tps, idle, or some other sensor that controls the idle, It probably needs to be recalibrated, but i dont kow if that would be the case, generally a simpel tap shouldnt throw off the calibration..

you dont have the check engine light on?

njamal

No check engine light on, yet.

mlevk

Check if you have coolant inside the spark plug's "passages" , it can become trapped
inside causing the plugs to miss fire , if there is fluids down there , just use a
Shop VAc to suck it out , I had a similar prolbem when I went through a large
puddle drowning the engine and water got trapped in there.

You have to remove the Black Plastic Engine dress covers to see the plugs.

njamal

Good suggestion, keep 'em coming, I am listening...

Thanks in advance for contributing.

persian451

why dont you just take it to a independent mechanic and see what he hasto say

mlevk

Did you find out what the cause was ?

njamal

I have not taken it to the mechanic and/or dealer yet. Local mechanics (3-4 I have tried) break this car apart when they try to look for stuff and try to take off nice secure coverings that our car has (I don't trust them anymore).

Dealer wants to charge me $96.00/hr. to look at it. I am not giving them that yet.

Previously, I did delay my full tune up. But, the car was running fine and I wanted to save up for Parts to do that. Then, came this issue.

So, I am treating this issue as the learning opportunity for me. So, I have been searching/reading the forums and have found that vacuum hoses when they get old & tough are to be replaced. And I did find one of the vacuum hoses to be lose if not completely off. I put it back tightly and the car's response has improved a bit. Not completely fixed yet. It may have a leak or something. This thing must have come off when I was working on the car replacing the hose. Becasue, it is right behind the hose.

So, next thing for me is to change all the vacuum tubing that I can simply get at Local Auto parts shops.

Please keep responding and keep listening. I will get to the bottom of it (hopefully without going to the dealer).

hyperopt

Can you describe the RPM fluctuation in detail? e.g. Does the RPM cycle between 500 & 1100 or does it stay at high RPM? Is the cycle predictable?

njamal

With my temporary adjustment to vacuum hose as described earlier, RPM went steady at 650-700 (without A/C) and at 750-800 (with A/C)

persian451

is there a hesitation when you rev it? it may well be vaccuum leaks or you forgot to connecta vacuum line

njamal

yes, hesitation still there, very minor. I believe that changing the vacuum hoses, atleast the ones Is aw lose will help me. Will it solve all the issues, not sure. But, this is better than what I was experiencing 3 days ago.

kamtra

Call me an idiot but I can't tell where in the engine I'm looking at in this picture. I got really friendly with my vacuum hoses after I inadvertantly broke a few of them off while changing the timing belt last month. My car has 130,000 miles as well and never hesitated before. These hoses got very brittle over the years. When they broke the car started stalling/dying. Made me sad! I'd check to make sure non of them cracked while you were unscrewing something or other. You didn't happen to change the intake filter did you? I tried a custom K&N cone on mine and the MAS freaked out- had to change it back to stock. Now all me hoses are new and the car is fine. Are you leaking power steering fluid into your intake? Those vacuum hoses sometimes carry fluid from the pump after the seals inside go bad. I have a long post about this matter somewhere. I'll go look under my hood and see if I can see what your messing with.

kamtra

I'd check the plugs for moisture. I'm not sure what all the vacuum hoses are on the engine there, I don't have my service manual yet. I always assumed they were part of the cruise control. But if there was coolant leaking there then there's a good chance of a pool of coolnat submerging your plug wire connection.

njamal

well, I replaced the vacuum hose that I thought had leak. RPM steady now. But, car stutters when accelerating. Plus check engine light comes on and goes off after a while.

Added techron to the fuel. Gave it a good 75 miles an hour drive for 50 minutes. No improvement. Still stutters, check engine light on/off at times.

Next, I will check the Spark Plugs to see if moisture is there.

Keep listening and contributing.