The hotter it is the worse my car drives - Toyota Nation Forum : Toyota Car and Truck Forums

teamssc · 06-10-2011, 01:00 PM

I have a 1998 Corolla that I bought in January with 135,000 miles and it has run great until the last three weeks when the outside temperature is 85+. It will run smooth and shift normal coming to work in the morning, under 80 degrees, but about lunch time after I drive for about 10 minutes it starts to "bog down". It's driving like I've got my foot on the brakes. It gets worse the longer I drive, unless I get over 60 on the freeway. If I get into stop and go traffic it runs like crap again. At first I thought it might be the transmission because Feb to April I did a fluid change, drain and fill 3 times and filled with Mobile 1 Synthetic. I changed the fluid 1 more time last week but it didn't help. This week I got a MAP sensor and it does idle better but I still have the problem within 10 minutes of driving. Almost the only way I can keep it going is if I really get the RPM's up. I just noticed when I got back from lunch the brake pedal has almost no travel and is hard to push (normally not hard) and I'm thinking that has also been happening when it gets hard to drive. As far as pulling codes I didn't think to do that before I replace the MAP and since I replaced the MAP the light has not been on. I took the battery cable off overnight when I did the MAP.

So what I'm I fighting and how do I address it? IAT? TPS?

Thanks

eberbs1 · 06-10-2011, 02:36 PM

If your brakes get hard is sounds like you might have a bad brake booster, that could also explain the issues you are having while driving due to the fact that a bad brake booster could cause a big vaccum leak. Check the big vac line going from the intake to the brake booster.

teamssc · 06-10-2011, 03:46 PM

Quote:

Originally Posted by eberbs1

If your brakes get hard is sounds like you might have a bad brake booster, that could also explain the issues you are having while driving due to the fact that a bad brake booster could cause a big vaccum leak. Check the big vac line going from the intake to the brake booster.

So maybe as it get's hotter it leaks more? And thanks I will check and report back.

***REN69*** · 06-10-2011, 08:54 PM

is it overheating?? I bet it's either the cooling system or a plugged up cat.

teamssc · 06-10-2011, 09:14 PM

Quote:

Originally Posted by eberbs1

If your brakes get hard is sounds like you might have a bad brake booster, that could also explain the issues you are having while driving due to the fact that a bad brake booster could cause a big vaccum leak. Check the big vac line going from the intake to the brake booster.

You're advice is great. Thank-you! I pulled and plugged the vacuum hose and drove for an hour with no problems. While I was at it I used the vacuum line and fed Sea foam into the exhaust manifold. I don't necessarily think that will fix my booster problem but it sure helped the engine run great. I've yet to hook up the vac hose and see if the problem has gone away. My guess is I'll still need to replace the brake booster. I'll report back when I know more.

teamssc · 06-10-2011, 09:15 PM

Quote:

Originally Posted by REN69

is it overheating?? I bet it's either the cooling system or a plugged up cat.

No, not overheating. Looks like it's the power brake booster. I'll know more after tomorrow.

teamssc · 06-11-2011, 02:50 PM

No question it's the power brake booster. Disconnected the vacuum line to it and drove all evening last night and for a few hours this morning without problems. Then put the vacuum line back on and brakes were locking up in 5 minutes. Took it off and drove fine. Just ordered a new brake booster and will have it Tuesday. Can't wait to get back to normal.

Also I wish I would have posted this thread before I spent $80 on a MAP sensor since that wasn't it! ARGH!!!!

90 GP · 06-11-2011, 03:40 PM

Give that master cylinder a good check over when you do the brake booster. If it has any seepage now would be a good time to replace it.

teamssc · 06-11-2011, 05:44 PM

Quote:

Originally Posted by 90 GP

Give that master cylinder a good check over when you do the brake booster. If it has any seepage now would be a good time to replace it.

It's real clean so I guess it's ok?

90 GP · 06-11-2011, 05:51 PM

Quote:

Originally Posted by teamssc

It's real clean so I guess it's ok?

I was thinking of possible fluid leakage past the seals which you couldn't see from outside. Check it out for seepage when you remove it from old booster to transfer to new one.

teamssc · 06-11-2011, 09:57 PM

Quote:

Originally Posted by 90 GP

I was thinking of possible fluid leakage past the seals which you couldn't see from outside. Check it out for seepage when you remove it from old booster to transfer to new one.

Will do. That's for the added direction!

teamssc · 06-19-2011, 02:36 PM

Turns out the new booster didn't fix it. With the vacuum line on it still begins to seize up in about 15 minutes of driving. With the line off it takes longer unless I have a lot of stop and go and then it happens quicker. I just had to stop in a parking lot and wait with the car off for about 5 minutes for the brakes to loosen up. It almost sounded like the rear brake shoes were letting loose while I sat. I guess new calipers are next?

teamssc · 06-20-2011, 06:34 PM

I did the rear wheel cylinders and didn't notice much any improvement. The brakes would still seize up in 10 to 15 minutes of driving. Then I realized I hadn't reset the computer so I took the battery cable off for several hours last night. Then driving it today it's a lot better though I'd say 20 minutes into my drive I could feel the brakes starting to tighten up again. Not extreme like it was. If there is a vacuum leak then I guess at this point that it would be in the line from the Power Drum to the block. What kind of hose would I replace that with? Also should I go replace the front calipers and the master cylinder?