Toyota Nation Forum banner

1 - 20 of 57 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
Fairly recently I've been experiencing the rough idle issue, where the engine is warm and pull up to a light and the idle will dip from 800 to about 500 shake the car and go back up (no AC or fan on). It will do this a few times, sometimes it will stabilize out again at 800. The new thing I noticed is that if I'm parked and in neutral and I hold the RPMs at about 2500, the same things happens. With no change in foot pressure the RPMs will dip about 300 and return over and over again. I was using my ODBII scan tool and hold the engine speed steady to read the O2 sensor output. No CEL.

I've scoured the forums and I haven't found a good solution yet. I've installed new plugs and air filter. I removed the throttle body and cleaned in really well. I also cleaned the MAF.

A lot of people have had this problem. Has anyone replaced the throttle body to see if that fixes it? A reconditioned one on ebay is about $70.

I've also had the extended cranking problem a couple times so I'm temped to bring the car in for that. Maybe it is all related and they can flash the ECU for the extended cranking and everything will be fine.

What are your thoughts?
 

·
Registered
Joined
·
9 Posts
Discussion Starter #2
I hold the RPMs at about 2500, the same things happens. With no change in foot pressure the RPMs will dip about 300 and return over and over again.
Basically I'm wondering if anyone else with the rough idle and vibration issue has the same varying engine speed under no load at a higher rpm. I don't believe this whole all Toyotas do this. I've had the car since it was new and it is only a recent problem.
 

·
The Neurotic One.
Joined
·
66 Posts
Basically I'm wondering if anyone else with the rough idle and vibration issue has the same varying engine speed under no load at a higher rpm. I don't believe this whole all Toyotas do this. I've had the car since it was new and it is only a recent problem.

I think the closest I've experienced to this is occasionally when I start the car it'll do a high idle (2k RPM) for a good 2 minutes. Maybe once or twice during this I've needed to touch the accelerator to get it back down.



As far as the rough idle issue, Mine seems to have nearly stopped since I swapped out the intake for a aftermarket one. I know that probably sounds odd, but since I did the swap my car hasn't once dipped and started shuddering like it used to. The RPMs overall seem much more steady now. Also for record I'm not saying it has completely stopped, it just has not been the dropping into 4-500 rpm. Biggest drop I've seen was down to 600 and that was a single time and didn't shudder.
 

·
Registered
Joined
·
7 Posts
By swapping the “intake” do you mean the intake plenum or the air box that houses the filter. I’m experiencing the same issue but it could be cause by a small vacuum leak as well.
 

·
Registered
Joined
·
5 Posts
Have a 09, 148k with very similar problem. if i come to a light the idle slow to the point of the car shuddering then in about 5 secs it stabilizes. It's been getting steadily worse and now it surging pretty much when ever it idles and it's very rhythmic, up then down, up then down, etc etc. Driving me crazy as I've replaced intake mani gasket, cleaned TB, replaced plugs/coils, cleaned injectors and run a bunch of tests in Techstream and I can't find a thing. I would've ignored if stayed the same but, as said, got worse and now I'm getting misfires on Cyl #4. I'm going to replace the injector #4 though I'm sure it's fine. Don't know what else to do at this point. Can't even pass inspection in NY where they're very strict and any codes or incomplete monitors are an immediate fail. Good luck with yours. I'll let you know it I find anything.
 

·
Premium Member
Joined
·
14,560 Posts
A bad O2 sensor could be causing that, if it's swinging too far rich or lean it could be causing the closed loop fuel trims to push the engine too rich or lean and make the idle dip as it swings one way or the other. The engine fuel trims are always following behind the O2 sensor reading by about a second but scan tool data may be too slow to pick up on the waveform from the sensor and show it's up and down swings very well. At about 100k miles it's time to change the upstream O2 anyway, that's roughly how long they last. It may not help but it's an easy part to swap and try that's probably end of life anyway.
 

·
Registered
Joined
·
5 Posts
I've got very similar problem that I may have made worse. 148k - ran perfectly till month ago. Started noticing when I come to a light the idle drops and occasionally starts chugging but seems to straighten self out after 5-7 secs. I've replaced intake gasket, plugs, cleaned TB, cleaned injectors, new coils and can't find anything obvious in Techstream. When I run active test to turn on injectors, the air/fuel mixture sensor voltage is perfect. I was ok with it but then I started getting random p0304 and now it's regular, almost every day so I gotta fix it. If i look at the FF data in Techstream it show misfire counts for cyls 1-4 at 0 and misfire counts for all cylinders at 87 yet I always get ONLY p0304s. I've checked resistance/voltage on all kinds of sensors and the ecu and everything looks ok so this is driving me crazy and making me broke. Now I'm thinking a flaky fuel pump because I dont know where else to go with this. Don't know much about Techstream but the misfire data is definitely confusing and contradictory. BTW, the p0304s starting coming before I touched anything and were getting more frequent when I started to try to "fix" things. The idle is now higher but I don't know if something i did or just the problem getting worse. 1 other thing is it has become rangy/surging at idle. I also seems to throw p0304 when colder. gets smoother as it warms up.
 

·
Registered
Joined
·
7 Posts
Have you checked the pcv and other vacuum lines? I have a 2013 so my pcv is going to be a task to get to. The fuel pump is also a neat idea but could you use a fuel pressure gauge during a “hesitation” event and see if it could be the fuel regulator or pump? Just guessing as I’m new to these Corollas
 

·
Registered
Joined
·
5 Posts
did a smoke test and didn't see anything. Replaced the PCV being it was only 7 bucks. The PCV hose seems good but I've been thinking of replacing it though those damn things are hard to find. I keep thinking this should be simple because it's always in #4 but guess not. I wish I could get more info on my Techstream readings which make no sense to me and don't indicate necessarily a problem in only #4.
 

·
Registered
Matrix
Joined
·
101 Posts
Sounds like a bad engine coolant sensor (ECT). I’m guessing your 09 has a 2ZR engine. On the 1ZZ your describing the classic intake manifold and or ECT problem. Ive not heard of intake manifold issues on 2ZR’s (doesn’t mean it doesn’t exist) but I’d bet dollars to donuts its just a bad ECT sensor.
 

·
Registered
Joined
·
7 Posts
I’m curious how the ect would alter the idle or combustion aspect in general but I guess weirder things can happen.

Regarding the smoke test, that can always be tricky especially when the cooling fan kicks on or your outside and it’s remotely windy. In the past I’ve tried the propane torch test. Turn on the torch without lighting it and move it around the vacuum lines. If there is a leak the engine should surge a little bit I’m not sure how a big the leak has to be for it to be clearly noticeable.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #14 (Edited)
A lot has happened since I started this thread back in June. I was wrong about the RPM fluctuation at higher speeds, it was just the sensitive pedal. A few times now I've been sure I had it all figured out but I was wrong.

1. Fuel Filter - I convinced my self that the fuel filter was plugged and was running in bypass (if it even has a pressure bypass). It made sense to me that when the idle dropped it was due to the bypass shutting and the fuel pressure dropping. I picked up a cheap Chinese fuel pressure test tee that goes in the push-to-connect disconnect by the clutch and brake master cylinders. I pulled the fuel pump connector under the rear seat and bled pressure by cranking the engine. Fuel pressure was great and never changed when the idle dipped. I did the fuel filter anyway. Didn't change anything.

2. MAF - I did the resistance checks on the MAF. It was fine.

3. Coolant temp sensor - This the one on the side of the block above the transmission. Did the resistance check it was fine.

4. Crank Position Sensor - Back of engine, two wires. Did resistance check it was fine.

5. Plugs - replaced, no change.

6. Injectors - When I had the test tee in, I used a injector pulse timer to check each injector. They all had the same pressure drop.

7. Intake Gasket - Did a smoke test on the intake, no leaks. Replaced the gasket anyway with an OE gasket.

Shortly after this we had a cold morning in CT. The car would not start. Never had it not started in 10 years. I probably tried 20 times. I had the neighbor come over and we checked for spark. It had spark. I had it towed to the dealer. They got it going and said the plugs were fouled and MAF was reading wrong "sometimes". They wouldn't trouble shoot it anymore until those were replaced. I reluctantly said OK. They also said they did a compression check and it was good. I felt better knowing the engine was fine. I now wonder how they did the compression check. Was the engine warm or cold, and did they only pull one plug at a time.

I mentioned the few times it had the extended start and they put the new software on it. They noticed it was having the idle issues. They said it was due to my injectors leaking by "sometimes" and "pockets of bad gas in the fuel system". For $1200 they would drain the fuel and put new injectors in. I said NO.

I took it home and put four new denso 232500T020 injectors in. They are the toyota OE and only $130 for 4 vs. $110 each from toyota. No change.

Next we had more cold weather. The car started to really have trouble most mornings. Now I'd learned the trick of holding down the accelerator pedal to cut the fuel and get the flooded engine to clear and start. I also finally started to get codes. Either cylinder 1 or 4 would have a misfire when it finally started. Some mornings still no codes.

Recently I found a post that sounded very similar to mine but the owner had more driveability issues. My car drives alright but lacks low end power. Also the fuel economy has dropped to about 28 mpg. This post determined that it was a head gasket leak between cylinders. The poster hypothesized that the idle fluctuations could be beginning compression lost. I picked up a leak down tester and sure enough when I pressurize #1 at TDC, air comes out the #2 spark plug hole. When I test #3 I get air out #4. I didn't bother testing 2 and 4. I think the leaks are small since the car still runs pretty well. I think it is worse when it is cold and things shrink opening up the gap.

I just bought all the parts I think I need to fix it. I'm going a little cheap since the car already has 187k. I got the timing chain guides and head gasket from toyota. They rest I got aftermarket (intake/exhaust gaskets, exhaust doughnuts, TTY headbolts, timing cover crank seal, and valve cover gasket). I plan do start the job next weekend. I need to get my '91 pickup on the road so I have a second car. It is almost done.

I hope the head gasket fixes the idle. I know it will fix the hard start. Some people replace the head gasket and it does not fix the idle. I think there are a lot of things that could mess with the idle. I'll post pictures and an update with I start the job.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #15
You guys that are now getting the misfire too, check for cylinder leak down. I got the harbor freight tester it was like $25. Not sure how good it is, but it did come with a 14mm adapter so I could pressurize the cylinders. I didn't really use the leakage severity gauge that is on it. For finding TDC I used a wooden dowel I had and put it in the spark plug hole then turned the engine over by hand until the dowel was at its highest point. Then I tested it. I didn't know if I was at the top of the compression or exhaust strokes so I turned it over again and tested it again. Then I repeated on
the other cylinder (I only did 1 and 3). With all the plugs out its not too hard to rotate. I turned the pulley on the alternator.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #16
Head gasket Fail with pictures

Got the motor apart yesterday. It was indeed the head gasket. I pulled the whole motor out the top of the engine bay with transmission attached. I had to do the drivers side CV so figured it was just easier to do it this way. I also wanted to do the clutch because I don't have to have to pull the motor again. Took about 4 hours to get it out.

Here is the break between cylinders 1 and 2:


This is the break between 3 and 4:


Once I lifted the gasket my hopes and dreams were crushed. The block had some nice "steam cuts" right where the gasket failed. I knew I had to have it machined. So much for putting it all back together today. I had thought about finding a used engine, but why wouldn't the same thing happen again. Also I know the entire maintenance history on this engine. The rest of the engine looks great inside.

I dropped the stripped block and head off at the machine shop this AM. Sounds like it will be about $250 for the work. I decided to go ahead and get rings, and rod/main bearings. Now that I know how to read the codes for the bearing mark numbers I'll put the same ones back in that were originally put in. The exhaust seats are a little pitted so I clean those up and put new exhaust valves in.

I'll post more pictures as I go.
 

·
Registered
Joined
·
7 Posts
So much for hoping it was the pcv..... yikes.

How many miles? If this happens to a lot of Corollas this might be a class action suit, similar to timing chain issues with early 2.0 vw Tsi motors. Mine does this with only 68k but I didn’t buy it new, I’m second owner so I’m wondering if it’s still within warranty?
 

·
Registered
Joined
·
9 Posts
Discussion Starter #18
I lucked out in the past with my first '91 pickup. It blew a head gasket soon after I got it in 2005. I looked up the parts I needed and I came across a notice that mentioned a service bulletin for the 3.0L head gaskets.

I called the dealer they took it in and fixed it all. New short block too all on warranty work.

If the rough idle dip is caused by a bad gasket then there are a ton of these out there. Maybe they would do a similar service bulletin. I'm sure every car is different. I hope that when I get mine back together it doesn't have the idle problem. If it does that I have no idea what it could be. I replaced everything except the throttle body. Maybe the worm gear in the throttle body gets worn.

My car has 187k on it. I hope to get another 100k.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #19 (Edited)
While I've been waiting for parts I started to clean up the rough casting in the intake and exhaust ports. Probably won't do a thing but hey why not. They are pretty smooth it start with.

I need to clear up the exhaust seats a little. I've got a set up Neway seat cutters that work really well. I don't want to take too much off, just enough to clear up the slight pitting. The valve train has hydraulic lifters so I hope there is enough clearance for the slightly higher seats. I'll check it when I bolt the cam section back to the block.

Years ago I bought a old MR2 Helical LSD (#41301-AE000) that at the time I was sure fit the C59 transmission. Toyota says to pull the engine if you want to do the clutch so I figured now was the time to do the LSD and clutch. When I split the trans the other day I found out I was wrong. The bolt circle for the ring gear is a lot smaller. Sooo I ordered another used MR2 Helical LSD (#41301-20230). This one does fit. It is the same one that Monkeywrench Racing sells https://www.monkeywrenchracing.com/product/trdtoyota-helical-lsd-lotustoyota-c5x-c6x-used/.

It put it in with used bearings this morning and no ring gear to just get an estimate on the bearing preload. It is a little tight. It makes scene to me that it will only get tighter with new bearings. I found this site: http://www.tcorolla.net/overhaul-1203.html which gives the specs on preload. It is for a slightly earlier corolla but I doubt the preload changes much. It says new bearings should have 6.9 – 13.9 in-lb starting torque. I used a blind bearing puller loosely tightened in the diff case with a 1/4" torque wrench. Mine woudl brake loose between 10 and 18 inlb. I have the old cones that came on the LSD and the old races from the open diff. Maybe that adds more preload. I'll put the new bearings in tomorrow AM to see if it makes a difference. I ordered the next two smaller shim sizes from toyota this AM. They said there is no ETA on the shims. I really wanted to get everything back together over the long weekend.

 

·
Registered
Joined
·
9 Posts
Discussion Starter #20
The corolla lives!!! Finally got everything hooked back up yesterday. It started right up. Then I smelled gas. I shut it down and one fuel rail was leaking terribly. I had pinched one of the injector o-rings when I put it in the fuel rail. Luckily I had those other 4 injectors so I stole the oring of one and carefully put it in with a little gasoline lubrication. I let it run for awhile and come up to temperature. The idle fluctuations were gone. I'll keep my eye on it.

The check engine light was on with the P0031 code for the O2 sensor. I kept clearing it and checking the wiring but it kept coming right back. I tested the sensor and it was bad. It was open across the B+ and HT pins. It was fine before I did all the work. I think I damaged it when I was beating the captured nuts off the back side of the exhaust flange. I should have gently cut them off instead. The impact must have broken something internal to the sensor.

The last issue I had was an oil leak from the cam chain tensioner. I don't know what I was thinking using the old one again. To fix that I pulled the valve cover again and made sure cylinder 1 was at TDC. I cleaned off metal gasket and put a little RTV on it. I waited a day and started it back up, no leaks.

Now I'm just waiting for my new denzo O2 sensor. I guess I could have driven it open loop but I figured I'd just wait. Once the sensor is in I can drive it a bit to make sure the new diff is all set. I really don't want to pull that engine again.
 
1 - 20 of 57 Posts
Top