m0098es

Hey everyone! My name is Matt and this is my first post. I am hoping to get some help and input on troubleshooting the cause of my 98 ES300's misfiring problems. I've been doing some troubleshooting trying to narrow the cause down but figured I'd post here since I've been reading DIYs and other troubleshooting threads on here so extensively. This is definitely a great and incredibly useful site and I'm glad to have found it.

This car was given to me because it's previous owner (my uncle) took it to a Midas where they obviously didn't know what they were doing or how to troubleshoot. They basically threw tons of parts at it to the tune of $5k over three months and that's when my uncle walked away. It sat all last year until he offered it to me and I figured I'd take a chance trying to fix it myself, or worst case, try and take it to an actual lexus/toyota specialist (one shop here has been specializing in lexus/toyota for 30+ years). But I'm hoping to narrow the causes down and try and fix myself, if possible.

Here are some key symptoms:

--The car will noticeably misfire, sputter, and have lack of power but only when warm/hot. When you first start it up cold and run it you can rev it and drive, but once it's up to temp, you're in trouble.

--It does drive, barely, and when doing so it is worse on hills, coming from stops, accelerating, etc. Aside from the misfire and engine/power trouble, you notice a lot of hesitation, and bucking. Misfire sounds (popping) are noticeable in the manifold area under the hood.

--When it's in "it's state", you can't rev the engine to 3000 rpms. You'll keep pressing down on the accelerator and it will just struggle to get to 3, misfiring.

--The exhaust is very rich smelling, but I'd think that would be common during a misfire.

--After a little while of trying to run it (or driving it), the car will die when hot. You can't start it up while hot/warm and need to wait for it to cool down before starting again.

I wasn't able to run the OBD test when I drove it a few months ago. But now the car has been towed here, and although not currently registered, I was still able to pull codes from just idling in the driveway. I got P0300 and P0301, 03, 05 codes which tells me the issue is somehow only affecting bank 1 - the side nearest to the firewall.

Some of the work that was done in early 2011 includes:
(This is only according to the Midas receipts)
Spark plugs
Wire set
Oxygen sensor
EGR valve
Alternator
Valve cover
Timing Belt and tension belt
water pump (you can see at this point they just decided to throw a bunch of stuff in and bill him)
Drain plug/upper + lower oil pans
Plenum gasket
Catalytic converter


I am not sure if when they replaced the EGR valve they also replaced the sensor too. Looking at the AutoZone EGR valve it appears to come with a sensor, but this one on the car is incredibly rusty - one of the bolts even looks borderline corroded. I did try running the car with the EGR position sensor disconnected and it was like you sped up all of the issues- the loss of power, etc came even though the car was still cold/cool. I didn't try to rev/run it enough to hear misfiring though.

This weekend I bought an ignition coil and swapped each one out with the new one to test that (there are only 3 as far as I can see). I don't think it's the coil or spark plugs or wire set. I also did a visual test of any tubing to check for cracked hoses and as far as I can see I don't notice any leaky hoses.

I was reading that some causes of hot start issues can be either the cam shaft sensor or cam position sensor. I pulled the cam sensor and the wire/connector is frozen to the sensor, so that's interesting -- but if it were bad, I think it wouldn't affect just one bank (though could I be wrong?). As far as I can see there is only one cam sensor.

Something else I checked out was the MAF sensor. I looked at it with a flash light and I can clearly see the sensor, no buildup or black crud or anything on there. So although I guess it could be bad again it doesn't look dirty.

Sorry for the extensive writeup here, but I felt like more information could be better than less. Here is my short list for things to check out:

-Timing gear; I've read a LOT about how being 1-2 teeth off can mess up one bank. This has recently been moved up to the list after research yesterday
-Cam position sensor (controls fuel, also affects hot starting; again I cannot get the connector off the sensor, it's stuck on so I wonder if this is bad, but if so, how would it only affect one bank?)
-Crank position sensor (controls spark)
-MAF sensor (I think this is possible but unlikely)
-Air intake temp sensor (this is in the MAF sensor, but controls air flow to the engine as you may know)
-Coolant temp sensor (works with air temp sensor to control air flow)
-EGR position sensor (looks rough from outside but it may have been replaced last year with EGR valve)
-Throttle position sensor (but would this affect only one bank?)
-MAP sensor
-Fuel system (could be a fuel pressure issue; I read on another forum that someone had a clogged fuel filter)
-I would like to check out the hot start issue more, to see if when it does not start if it is a fuel issue or spark issue. I can't smell any fuel though.
-Vacuum leak
-Ground wiring issues
-Intake manifold gasket leak (I don't think I could test this, and most other vacuum leaks myself)
-Not a sensor; something mechanical?

Any ideas on what to check out first and tips for troubleshooting? I am starting to run out of ideas but I want to test as many things as I can to save $$ before taking it to a specialist. What sucks is that the codes are JUST misfire codes and nothing really specific.

Thanks in advance!

GS4_Fiend

iTrader: (22)

First, find out which cylinder is misfiring then report back.

m0098es

Hi GS4, thanks for replying! The codes I got were for P0300, and then P0301, P0303, P0305 - so cylinders 1,3,5. The bank closest to the firewall. I will need to keep running the car and seeing if the codes persist, or if the cylinders jump around, but as of this weekend that's the code I got.

Any tips, thoughts, ideas, etc would be much appreciated.

How possible is it for one to get a misfire code and have it be an issue with a sensor, despite no code for a bad sensor?

GS4_Fiend

iTrader: (22)

I suspect the VVT Oil Control Valve is bad on bank on to cause all of the cylinders 1,3 and 5 to misfire at the same time. Its a common problem on these cars when that OCV becomes defective. But you must rule out the basics first such as spark and fuel before changing the OCV for bank 1.

m0098es

Are you sure the OCV would apply to my car, and that it has them? I looked in one thread on here, as well as Wikipedia (on both the Lexus ES 300 pages, and the Toyota MZ engine pages), and both are saying that VVT-i wasn't introduced until 1999. Like I said in my post, this is a 1998.

The OCV issues sound like my problem exactly, and taking out the cam position sensor I did notice some sludge. That would make it plausible that the OCV could be gunked up, but is it even on this year ES model??

If you are sure my car has an OCV, do you have any information on where I can find diagrams, etc? I tried searching extensively in the service repair manual but cannot find anything on it.

m0098es

I just checked the vin with a parts site and the site confirms that both parts (OCV filter and OCV) do not fit my car. To be sure I also called a dealer here, asked if the part number was in stock and asked what year it fits. He said 99. So this would fit in and confirm that this car does not have VVT-i or an OCV.

GS4_Fiend

iTrader: (22)

If doesnt have the OCV. I would check out the spark plugs, wires and coil. Next would be fuel injectors. Last would be compression. Do those 3 basics first.

m0098es

Just wanted to post an update to my misfire problem. We fixed 90% of the issue(s) by checking and replacing the crankshaft position sensor. It has fixed the issue with the air/fuel combusting in the manifold, as well as the hot start problem. The car also revs (up to 5, if you press that hard) no problem, hot or cold.

But the CEL is still on, giving a P0300 error code - same thing, multiple/random misfires. I've made sure to erase the codes repeatedly but it still comes back. The exhaust also smells rich and it definitely still has a rough idle. It's weird because you cannot hear any popping sounds like the there is combusting in the manifold, not like how it was before. When looking at the engine you can see that it will seem to shake about every second or so with the low idle. I am thinking of checking out the IAC or the TPS for the idling issue, but am not sure if that is related to the misfire code. Haven't really dug into the fuel system but I am sure a dirty system could be a factor. Thoughts/ideas?

There is also a bunch of rattling in the intake manifold but from researching that it sounds like it is a "thing" for these cars to have issues with the baffle in the manifold. It doesn't sound/seem like anything other than a sound annoyance, from what I can tell. That gasket had been replaced last year so I am pretty sure there's no leak.

The car is definitely drivable - not sure if it will pass emissions test or fuel economy, but it seems to be 90% fixed now.

P.S. Thanks for your thoughts GS. Even though the car ended up not having an OCV valve it did lead me to come back to checking the crank sensor which was bad.

GS4_Fiend

iTrader: (22)

The crank sensor would affect all cylinders not just bank 1. I would check spark plugs, wires, and last injectors. Do the simple things first. Its critical

MikeLex

Once I had a P0300 code on my 94 Camry V6. Symptoms were weird: Out of the blue the engine died or the idle became extremely rough. It turned out that a broken black plastic coil connector was the culprit.

m0098es

Just wanted to update this thread to help anyone who may stumble upon it in the future. The car is fixed about 97% now; it turns out the timing was off by 3 teeth, likely caused by some inexperienced Midas people when they changed the timing belt.

The crank sensor was definitely bad but likely only contributed to the timing problems in a small way. It did impact the hot start problem and detonation in the intake, though.

The timing being off with the car caused the following problems: baffle/rattling sound in intake manifold, loss of power/sluggish hesitation, surging when accelerating (shooting up from 3k rpms to 5k suddenly), hard/late shifting, shaking/bucking when in-between 2nd and 3rd gear, engine cruising speed was over 3k rpms, and the engine was generally really loud.

All of those things are now gone/fixed and the car runs like a dream. The engine is so quiet and I am really impressed with the power and acceleration that it has.

By the way, I ended up taking this car to a Lexus specialist (independent shop, but had dealer experience) and they got the job done. He said he can only think of one time in 20+ years where a car was this messed up causing these kinds of problems.

The car also had a failing PCV valve (almost entirely seized, except for a little bit of rattling). It was probably still working, somewhat, but it cost a whole $5 and 5 minutes to fix so I am glad that is out of the way.

The only thing that is wrong with it is a couple of trouble codes and poor fuel mileage; I talked to the mechanic about that and will post in a new thread because it's a different issue from the misfires/timing.

Thanks again to GS4 and MikeLex for your help with answering my questions a few months ago.

lilninja

i would have almost been able to bet money on knock sensors being root cause of problem because my car had same problem when i bought for 350 and knock sensors fixed it. congrats though man