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Discussion Starter #1 (Edited)
I just installed my Maxbore 70mm TB and the idle is jumping.

Here is the video of the rev meter. http://youtu.be/FeV917jfOC8

How do I fix this?

I have IM Thermal Gasket, Ported stock IM, thermal TB gasket, Maxbore 70mm bored TB, K&N Typhoon intake.

Your help is greatly appreciated!:wavey:


I forgot to put that I do have the Cobb Tune for the K&N Intake. Will this cause a problem? Should I set it back to stock? or does this matter. The tune worked very well before I but the new TB in.
 

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Do the idle relearn, let me know if it fixes it. I have a tsx tb that I cant get to run right as well, even after the relearn.

disconnect battery
turn key on, wait 2 secs
hold rpms at 3000 till you reach 194 degrees or till radiator fan kicks on.
let idle for 5-15 mins, if it works the idle should level off to a steady idle.

shut off engine and turn the key to the on position, the cel will light up for the first 20 secs and flash 5 times confirming an idle relearn.

My car won't relearn the idle after this, so I put my stock one back on. No problems.


I downloaded and flashed a flashpro tuning map with the tsx tb as a mod and it idled perfectly fine with my tsx tb. Only problem was the map was set for bigger injectors (370) so it made my car run lean on the stock injectors. I added a bit more fuel to the map and it messed everything up again.

I currently went back to my stock tb and street map.
 

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Discussion Starter #3
Hi Streettuned,

Thank you for the info. I thought I did it but I didn't totally remove the battery at install. Just the negative terminal. I wonder if that is an issue.

Tomorrow morning I'm going to check everything (connections), remove the battery, and do the re-learn. There are some possibilities that there is a leak somewhere (from what I read in other threads).

Is there a problem is I drive it in this condition...??

I live in a mobile home community and I don't want to keep bothering my neighbors with this noise. I figured I take it out to the street or to an empty parking lot. My work is 12 miles away...
 

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Discussion Starter #4
Okay...

So I tried to relearn and it still did the same thing.

My thought was to start with least involved things so I un-installed my Cobb from my ECU.
This helped. The car would settle down and land around 1500rpm. BUT... when I drive it the RPMs shoot up over 5K when I shift. When I stop it bounces a bit and rests at 1500rpm.

I took the TB out and put my stock TB back and everything is back to normal.

I know there is a post if you get a P1683 code. I got a P5070 which is an error code for "Idle Control System RPM higher than expected" with the bored TB.
So the post to fix the P1683 code won't help me...
I don't think it's a bad thermal valve since everything is fine when I change the TB back.

Is it possible that I need to ground the TB because I am using a thermal gasket?
I know you have to do this with the IM thermal gasket...

Thoughts?
 

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Discussion Starter #5
I have been contacting a few people.

I contacted P2R to see what they think. First, let me tell you how awesome their customer service is. I got a response very quickly and I appreciate their input. They basically said the symptoms don't point to a vacuum leak and is probably a problem with the TB itself. (I was wondering also if there could be an electrical issue because it isolates the TB from the IM. But I don't think this is an issue because people install the Spacers with thermal insulation with no issues.)

I also contacted Steve from E-Tunez since I will have them tune the car after I get this to work. Steve has been a wealth of information for me and has been recommending these upgrades. I think he is the one that posted the TSX TB install DIY http://www.8thcivic.com/forums/engine/181397-06-tsx-tb-install-info.html
He will be able to help with a DataLog but I will get it working first because I can't drive it safely at the current state...


In searching issues regarding Maxbore J-Ro seems to be the authority on TB issues. Here is his sticky with calibration procedures. http://www.8thcivic.com/forums/engine/222443-diy-throttle-body-calibration-procedure.html
I PM'd him and he got back to me with the following information:
At first glance, I would say that your situation is not the "normal" situation that I posted the procedure for. You were right to doubt it since you're not getting the P1683 code and your revs appear to be varying in a 1000RPM range, whereas in the situation I described in my thread, the range is only about 100RPM. You were also right to re-install the old TB, since that confirms that you're definitely dealing with a problem with the TB and not anything else.

If your throttle body bore diameter is large, I'm wondering if you're in a situation where the TPS voltage is still in-range (maybe just barely) but the large bore is letting too much air in and the ECU is trying to correct it by forcing the revs back down. This might explain the 1000RPM rev range and the P0507 code.
So I guess what I'm suggesting would be a modified version of the procedure....
Definitely Step 1 would be to measure the voltage on the new TB with the ignition in the ON (II) position (but the engine off). This will confirm/deny my theory above, and will tell you how much adjustment is available to you before you actually go out of range and get the P1683 code (which we obviously don't want to do).
Step 2 would depend on the results of Step 1. If the voltage is high but in-range, I would say that looks good for the theory, and you could proceed with bringing the revs down bit-by-bit to see if the problem goes away. This would basically be Step 8 in the procedure, however you would have to periodically stop measuring to start the engine and check the idle condition.

I guess the good news is that I don't think your TPS is bad and I think this problem is correctable by calibration. If the above steps don't work, let me know. A second alternative could be to swap the TPS between your original TB and the new one to see what the effect is. Removing/installing the TPS is a pain without security Torx bits, so I would say leave that theory to last​



I am going to plug the TB in with the car on (engine off) and see what the voltages are and go from there. I Probably won't get there until Friday since I work through Thursday and I'm not home when there is sunshine...


I will post my progress as I have more information.

Any input from you anyone is greatly appreciated!
 

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Discussion Starter #6 (Edited)
I got a reply from Maxbore.
Here is what they told me.

The ECU is programmed to run on the smaller TB. The bored TB is much bigger and will flow more air at the same throttle angle. You must not move the adjusting set screws on the outside of the TB, that is a sure CEL.
Please disconnect the battery for a good 10 minutes and then restart the car with the bored TB. Let it idle a few minutes. It might take several tries and driving the car like that for a while until the ECU adapts to the TB and also for the TB to break in and seal completely.​


Is this right?
I'm going to give it a try on Friday morning when I can drive it to an area where I don't have to worry about noise...

Will my computer have to go through this process everytime I unplug the battery or re-flash the ECU?...

Input please...
 

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Discussion Starter #7
This is what J-Ro has to say about the Maxbore answer...


Well, he's right that the larger TB will flow more air at the same angle, which is basically the same as what I said the other day. However, I don't like his "You must not move the adjusting set screws on the outside of the TB" comment... I (and others) have posted a ton of information about how the TPS works and how it interacts with the ECU. The fact that he's saying that moving the set screw at all will give you a CEL proves he hasn't read any of this information and is providing advice on his own opinion rather than fact. That kind of thing irritates me because that's how mis-information spreads.
In the second part, he's basically saying to do the idle-learn procedure (which you've done, if I remember correctly?). Even if you haven't, the idle-learn procedure may fix the problem and it may not, since the procedure is meant for setting small-scale variables such as fuel trim, and will typically not have a significant effect on throttle angle. It IS worth a try though if you haven't yet, as it's free and easy to do. However, he's wrong that moving the set screw will cause a CEL. Moving the set screw will only cause a CEL if the voltage is moved out of the range expected by the ECU. This goes back to what I was saying before about checking the voltage to see if it's on the upper end of the range, which then means that you CAN move the voltage down somewhat, towards the lower end of the range in order to close the throttle angle (but obviously not far enough to send the voltage out-of-range).

I'm not sure how Keihin does it, but obviously there is some kind of calibration procedure before the TB leaves the supplier's factory. They will have a target voltage range as well, which means that some TB's will be higher in the range and some will be lower (basic process control), which could explain why some TBs have issues after boring and some don't. It's naive of the Maxbore guy to ignore this variation and to assume that all TBs will throw a CEL if the set screw is moved.

Anyway, that's just my (long-winded) two cents
Let me know what you find out with this... I'd be interested to know how this pans out and what the root cause really is.​
 

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Discussion Starter #8
The Plan

Based on all the information this is what I'm going to do...


1. I will install Cobb AP and flash my ECU with the map from Cobb called "Installed Style Mode." Cobb says that "Stock style map. Uses stock fuel, timing, camshaft phasing, and VTEC values for conditions when you need the vehicle's ECU to act like it is still stock. DOES NOT UNINSTALL AP FROM VEHICLE." I know things settled when idling when I was in stock (no access port). This map should let my ECU act like stock but also let me data log if I need to. If this doesn't let my idling settle then I will uninstall AP.
2. Install the Maxbore TB. Check voltage on the Maxbore TB to see if it's in the acceptable ranges.
3. Run Relearn procedure. (If the revs don't settle after a few re-starts after the procedure I will uninstall AP from my car totally and do relearn procedure again and should settle the revs at 1500RPM)
4. I will drive the car carefully several times. Restarting the car several times as well.

--- I hope the car is running fine as Maxbore describes at this point. I will test further by disconnecting the battery to re-set the ECU and see how it reacts. Also remove AP and re-install AP. I don't want to have to go through a huge deal of re-learn every time I disconnect the battery or do a re-flash... ---

5. If not running right I will do the adjustment procedure as J-Ro outlined for me. (Do same ECU reset/re-flash to see how it reacts)
6. If still not working I will send it back to Maxbore to inspect/test and re-calibrate for me. (I am tempted to replace the TPS with my old TB but I don't want to mess with my working TB. I will give Maxbore the opportunity to test, inspect and calibrate.)

We will see how it goes...

What do you all think?
 

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Discussion Starter #9
With some time today I moved forward with my plan.

I flashed my ECU with Cobb's "Installed Style Mode v105c"

I plugged in the Maxbore TB and got the following voltages:
THL1 = 0.942V
THL2 = 1.758V

These are in the allowable ranges but on the high end.


I installed the Maxbore TB.
proceeded with leaning procedures but my revs bounced just like the video on my first post.

I tried a different Cobb map. I did "Installed Style Mode v103" and the revs settled to 1.5K but as soon as I pressed on the gas it started bouncing again. I couldn't get the revs to settle any more.

I ran a data log to send to Steve at E-Tunez to see if he had any information. The data log should show if there is a leak or not.


I ran out of time and put my old TB back in.


The map I flashed is the same as stock so I have Rev Hang again. it's been a while since I have had rev hang. I kind of like it though... I feel like I get into the next gear smoother. It's a little annoying when I am just driving at low speeds through a parking lot but I like it that the revs stay high when shifting and keeping me in the power band.


I am now waiting to see what J-Ro has to say about the voltages and Steve to take a look at the data log.
 

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Discussion Starter #11
I would try swapping the tps/motor from the stock tb...
I am thinking this is my next step but I want to see what the other results show.

I saw your thread about the gasket and wonder if that is my issue. http://www.8thcivic.com/forums/intake-spacer-discussion/264450-70mm-paper-throttle-body-gasket.html
I port matched my IM and wondering if that really thin edge on the TB is getting the right seal. I am using a p2R thermal gasket.
Mike_Si_29 posted that he was going to use silicone to seal the gasket but didn't post if it fixed his issue. I PM'd him to see what his issue was and if he was able to fix it.
We will see...
 

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Discussion Starter #13
Its a very strong possibility you got a vacuum leak and in this case the TB is useless.
http://www.8thcivic.com/forums/mechanical-problems-technical-chat/255333-problem-tb-idel-surge-help.html
I'm hoping Steve can see the data lot I took of it and prove that it's a vacuum leak...
Then we can put this to rest...

The fact that I did get the revs to settle at one point leads me to believe that there is something that is moving and causing things to change.
It can be temperature related with metal expanding/contracting closing/opening a seal. Or it can be something shifting with engine vibrations.
Either way it's not good. I can't afford an intermittent issue...
 

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Discussion Starter #14
Mike_Si_29 PM'd me back and has not tried the gasket glued to the TB yet...

He said he has the 3.7L TL OEM TB and has no issues with it.
How big is the opening (In and out) of this TB?
Is there a string that shows the sizes of the different OEM TBs we can swap? (I can't find one...)
 

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Not sure if this will help.

Have you tried spraying carb cleaner to check for a vac leak? With such a large surge, I'm not sure of you would even notice the increased rpms.
 

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Discussion Starter #16
Not sure if this will help.

Have you tried spraying carb cleaner to check for a vac leak? With such a large surge, I'm not sure of you would even notice the increased rpms.
Nope. Didn't try that...
I don't have carb cleaner... Would brake cleaner work? I have some of that...

I can try it next time I try installing it.
 

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No, brake cleaner doesn't work. I embarrassed myself terribly in front of my peers by assuming it did. Drop the $5 and get carb cleaner.
 

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Discussion Starter #18 (Edited)
I did some looking into the seal by looking at the P2R thermal gasket I am using.

I can tell the gasket does a great job because you can see all every little mark/indent in the metal in the plastic. I think that this shows that the material is good and does it's job.

I found that the bottom edge of the gasket shows more indent than the top. I should see a full circle indented around the gasket but I don't. The gasket sits a little High to the TB by about 1.5mm. At the top of the TB there is a very thin wall of the barrel they insert.

I also looked closer to the inserted barrel that Maxbore puts in. I found that it is not perfectly flush and may be causing air to leak. There are some holes through the barrel and into the chamber so I'm confused to what this means.
Can too much air to this chamber cause problems? If yes then the bad seal can be an issue. But if it doesn't matter then I am getting a good seal otherwise...

Below are pictures of the parts I am talking about.

Bottom of TB Gasket
View attachment 45161

Top of TB Gasket
View attachment 45162

TB Opening
View attachment 45164

Gap in Barrel to TB Body
View attachment 45163
 

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Getting back to your voltage measurements, your measured values were:

THL1 = 0.942V
THL2 = 1.758V


Where the ranges expected by the ECU are:

THL1: min 0.818V, max 0.943V, median: 0.881V
THL2: min 1.644V, max 1.766V, median: 1.705V


Your values are right on the top end of the range, so much so that I'm actually surprised that you haven't seen the P1683 code. The good thing is that both your THL1 and THL2 signals are in the same area of their respective ranges, so it still looks like the TPS is reading normally.
I know there are other avenues you want to try out, but to pursue the voltage route, I would say reduce the THL1 and THL2 readings to the median values above, check the idle, and if it still doesn't work, reduce it to somewhere in the lower end of the range, with a bit of a safety margin to keep it from going below the minimum values and re-check the idle.
 

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a search on the forum and you would see that MANY people are having and have had issues with TBs bored by maxbore. i would stay away from having them do it.
 
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