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Oh, no it does not. It has two fins that only work with the stock maf in the stock intake at stock diameter. If you're using a COBB or anything else even with fins it doesn't work just the same as the stock does. Honey comb in his COBB and it was night and day. Stable AFR, smooth idle, etc. Performs better than he can remember.
 

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Discussion Starter #82
Oh, no it does not. It has two fins that only work with the stock maf in the stock intake at stock diameter. If you're using a COBB or anything else even with fins it doesn't work just the same as the stock does. Honey comb in his COBB and it was night and day. Stable AFR, smooth idle, etc. Performs better than he can remember.
Ah, that can't be my problem then. I'm all stock.
 

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Try a new MAF?
 

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If the MAF went bad, the ECU would have a CEL like P0171. My MAF did go bad. ECU did show a P0171.

This MAF is a standard sensor used in most Toyotas and Hondas.

Op should borrow one from another car and swap in to check it out. If it solves the problem then replace it.

I bought a MAF from eBay for $25. It had DENSO and TOYOTA part number molded into the plastic housing. The MAF works perfect in a GTS and in a Lexus.
 

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Work Done, Sexy Time.
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So, I thought I'd update this thread. I'm still having major hesitation issues.

As 2way suggested, I've replaced the OCV screen/filter with a brand new one. The old one didn't look that bad to begin with. Needless to say, this didn't solve my problem.

I also did a compression test and got 181 psi across all 4 cylinders. The engine seems healthy enough.

I also sprayed down the entire intake manifold to re-check for leaks. Nothing.

Another thing I noticed is that the hesitation is 2x worse with A/C on. The car accelerates like it's running only on 3 cylinders with it on.

I'm running out of ideas here.
I'd bet good money that your real problem is your a/c compressor is starting to seize up. This particular issue has been discussed here before, has happened to me and will cause the issues that you are describing. When the rpms get high enough there's enough power to make it seem like the issue was temporary but it'll keep happening.
 

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Discussion Starter #87
If the MAF went bad, the ECU would have a CEL like P0171. My MAF did go bad. ECU did show a P0171.

This MAF is a standard sensor used in most Toyotas and Hondas.

Op should borrow one from another car and swap in to check it out. If it solves the problem then replace it.

I bought a MAF from eBay for $25. It had DENSO and TOYOTA part number molded into the plastic housing. The MAF works perfect in a GTS and in a Lexus.
I think if the sensor is lightly contaminated, it wouldn't cause the CEL to go off. How was the ebay MAF, any issues with it?

I'd bet good money that your real problem is your a/c compressor is starting to seize up. This particular issue has been discussed here before, has happened to me and will cause the issues that you are describing. When the rpms get high enough there's enough power to make it seem like the issue was temporary but it'll keep happening.
This is good to know. I figured the hesitation with a/c on and off was related, but seems like it is a separate issue now.
 

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Still getting a P0505? If so, solve that.
 

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My GTS had P0171.

I kept cleaning the MAF but did not solve the problem. Finally I swapped in another MAF, the problem was fixed. So the MAF was bad but there were no physical indications it was bad, eg. nothing looked broken.

So you should swap in a known-good MAF. The same sensor is used in CAMRY,COROLLA, LEXUS.

Make sure you reset the ECU by disconnecting the battery. The ECU will run full rich regime for a day or so until it learns the new sensor's output.

The MAF bought $25 from eBay works great, but it has DENSO part number on it. The counterfeits usually have no Mfr marking and has thinner Platinum plating on the sensor element, so would not last as long as the genuine Denso part.


I think if the sensor is lightly contaminated, it wouldn't cause the CEL to go off. How was the ebay MAF, any issues with it?


This is good to know. I figured the hesitation with a/c on and off was related, but seems like it is a separate issue now.
 

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Discussion Starter #91
I swapped out my original MAF with an ebay one today. I reset the ECU and everything. I've driven about 30 miles so far. Performance wise, there was virtually no difference between the two MAFs.

I'm open for more suggestions.
 

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FYI, it takes going through about a full tank of fuel for the ECU to remap effectively.

You have the stock airbox installed, yes? I know that you say 2-3K RPM is the problem range. But, is the ACIS butterfly still installed and functioning?
 

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Discussion Starter #93 (Edited)
FYI, it takes going through about a full tank of fuel for the ECU to remap effectively.

You have the stock airbox installed, yes? I know that you say 2-3K RPM is the problem range. But, is the ACIS butterfly still installed and functioning?
I'll see what happens after a tank then.

I'll check to see if the butterfly is still there, but it's kind of interesting that there is a how-to on how to remove it and it's considered a mod..
 

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The plugs' white tips

I just looked at the op's pics of the plugs. They are way too white, suggesting coolant was burned in the cylinder.

Op should warm up the engine then rev up to 2500 - 3000 RPM and watch the exhaust. If there is white smoke coming out, then coolant is leaking into cylinders likely from the head, or less likely, the block.

Op should do compression check of cylinders. If there are any cracks or leaks, the engine will hesitate at 2K-3K RPM. It will run smoother at higher RPM but will exhaust smoke and have lower horse power and gas mileage.

If you have cracks in the head or block, it's better to replace the engine with an used one. It's impossible to find and fix those fine cracks. Would be way too expensive compared to buying an used engine anyway.

Good luck.
 

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Discussion Starter #95
I just looked at the op's pics of the plugs. They are way too white, suggesting coolant was burned in the cylinder.

Op should warm up the engine then rev up to 2500 - 3000 RPM and watch the exhaust. If there is white smoke coming out, then coolant is leaking into cylinders likely from the head, or less likely, the block.

Op should do compression check of cylinders. If there are any cracks or leaks, the engine will hesitate at 2K-3K RPM. It will run smoother at higher RPM but will exhaust smoke and have lower horse power and gas mileage.

If you have cracks in the head or block, it's better to replace the engine with an used one. It's impossible to find and fix those fine cracks. Would be way too expensive compared to buying an used engine anyway.

Good luck.
I've checked my compression last week. I got 181 psi across all 4 cylinders. I'll have someone drive behind me and check if any smoke is coming out. I've never noticed any smoking myself. I get 30 mpg and I rev at least up to 3k in most gears.
 

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Plugs

How may plugs have white tips? Which cylinders?

That white stuff on the plug is burned coolant.

You have fine cracks in the head or cylinders which leak coolant into cylinders. Check it out

You dont have to drive it. Just park the and have someone rev it up and down to 3000 RPM. If any white smoke come out, it burned coolant. Any black smoke, burned oil in cylinders.



I've checked my compression last week. I got 181 psi across all 4 cylinders. I'll have someone drive behind me and check if any smoke is coming out. I've never noticed any smoking myself. I get 30 mpg and I rev at least up to 3k in most gears.
 

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Discussion Starter #97
How may plugs have white tips? Which cylinders?

That white stuff on the plug is burned coolant.

You have fine cracks in cylinders.

Check it out
All 4 plugs look the same. They are all white like that. I've had to bleed my coolant multiple times after cleaning my throttle body and replacing my IACV. During the process, I've revved it up to 3k while parked and I've never seen smoke pouring out.
 

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It's unlikely all 4 cylinders have leaks.

Any smoke coming out of exhaust when rev up and down?

It could be engine is running too lean. Something may be blocking the fuel line into the injectors.

Check injectors' pressure. Use a bottle of Toyota's injector cleaner or Techron cleaner. It may help.
 

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Discussion Starter #99
It's unlikely all 4 cylinders have leaks.

Any smoke coming out of exhaust when rev up and down?

It could be engine is running too lean. Something may be blocking the fuel line into the injectors.

Check injectors' pressure. Use a bottle of Toyota's injector cleaner or Techron cleaner. It may help.
I've never seen any smoke come out of the exhaust when revving up and down. I assume it would be quite noticeable.

I find it more likely that the engine is running lean. I've tried using fuel cleaner a few times, but it did not help. My fuel trims looked good, so I haven't really suspected anything wrong with fuel delivery.
 

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Coolant leaks

With the white residue on the plugs, you definitely have coolant leaked into cylinders.

The hesitation at 3K RPM is caused by the plugs being fouled up and not sparking.

This is a serious problem. I suggest you bring it into a good Toyota dealer for diagnoses.

If leaks are confirmed, you can try to use the radiator leak plug fluids. It would help.
 
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