Stupid question, did you ever get the header tested for a leak? Seems weird that no shops in the area could figure it out.
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Hesitation Mystery continues...replaced many parts
- Thread starter Zishan
- Start date
Stupid question, did you ever get the header tested for a leak? Seems weird that no shops in the area could figure it out.
Not a stupid question at all. They did find a leak, fixed it, and then found another leak at the collector. I was told they can't fix it however because it's stainless steel? Told me to purchase some "muffler cement." I'm going to take it somewhere else.
Might be worth the road trip to take it to SOS and have them knock everything out at once and get your baby on the road. I hope you get everything worked out, I can imagine its frustrating
Tried this.....it felt promising at first. The car ran a little smoother and felt more powerful...... but underload, it again started bogging and hesitating. :frown:
Thanks for the suggestion though,
- Z
Z, I don't know what to do say...:frown: I feel real bad about your car. I really wish you can get this problem resolve soon! It just making me sad and mad! 
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How much load in % of throttle position?
Maybe worth to install a wideband-o2 and monitor AFR unless you know it's too lean. But you can recognize when it starts to get lean.
Another part you didn't change: MAP-sensor.
Check all vaccum lines for rubbing, leaks and free-flow.
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I think I've encountered this similar issue as the OP a handful of times, all of them were on the freeway. However one thing to note that I've noticed is that the TCS light flickers when I feel that hesitation. Is that similar to anyones experiences or anyone know what might be the culprit?
What size tires are you running?
I ran a slightly off tire size setup once on my 18/19 set. Every so often when I changed lanes and ran over those bots dots TCS would pull back the throttle. It was worrisome at first until I figured out it was the tire sizes.
To OP, if this is your issue play around with your tire pressures a bit in the short term.
To OP, if this is your issue play around with your tire pressures a bit in the short term.
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I found this post and think there is some relevance here.<O</O
<O</O
http://www.nsxprime.com/forum/showpost.php?p=1521331&postcount=1<O></O>
<O</O
It basically talks about the EGR system and what happens when you block it off. How the ECU is still running EGR compensation maps and your combustion chamber could be running much hotter than necessary. This got me thinking, so I broke out the manual and went out into garage to test my EGR system starting on page 11-128 of the manual. <O</O
<O</O
It is very straight forward, so I will not bore you with all the details. However, what I did discover was zero vacuum on hose 5 (one leading to EGR valve itself). I hooked my gauge up and nothing. I then followed the procedure where you pull the 6 pin plug from the EGR Control Solenoid and apply a +12V source to see if the valve operates. I could hear it clicking, but there was no change on the vacuum gauge. Manually jumping the solenoid eliminates the possibility of a bad connection from the ECU to the solenoid. This test should give you instant vacuum (approx. 8”) when you apply +12V. <O</O
<O</O
My goal this weekend is to replace all the vacuum lines on the throttle body side of the car, and hopefully get the solenoid unclogged if possible. A new one is only $159, but I'm going to try the cleaning route first if possible?<O</O
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Wish me luck, but for once I feel very optimistic.<O</O
<O</O
James<O</O
</O<O
</Ohttp://www.nsxprime.com/forum/showpost.php?p=1521331&postcount=1<O
></O><O
</OIt basically talks about the EGR system and what happens when you block it off. How the ECU is still running EGR compensation maps and your combustion chamber could be running much hotter than necessary. This got me thinking, so I broke out the manual and went out into garage to test my EGR system starting on page 11-128 of the manual. <O
</O<O
</OIt is very straight forward, so I will not bore you with all the details. However, what I did discover was zero vacuum on hose 5 (one leading to EGR valve itself). I hooked my gauge up and nothing. I then followed the procedure where you pull the 6 pin plug from the EGR Control Solenoid and apply a +12V source to see if the valve operates. I could hear it clicking, but there was no change on the vacuum gauge. Manually jumping the solenoid eliminates the possibility of a bad connection from the ECU to the solenoid. This test should give you instant vacuum (approx. 8”) when you apply +12V. <O
</O<O
</OMy goal this weekend is to replace all the vacuum lines on the throttle body side of the car, and hopefully get the solenoid unclogged if possible. A new one is only $159, but I'm going to try the cleaning route first if possible?<O
</O<O
</OWish me luck, but for once I feel very optimistic.<O
</O<O
</OJames<O
</O
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Very interesting information about the EGR, James. Worth to look into it. I was dismounting the EGR unit during my CTSC install and noticed a small amount of deposits but not enough to call it clogged. On the Insight 1, it has three sources to not operate or to get a herky-jerky engine at part-throttle load: 1. potentiometer worn, 2. clogged EGR or passages, 3. valve stuck.
http://www.insightcentral.net/forum...on/16097-erg-plate-removal-cleaning-pics.html
EDIT: I've cleaned the passages on my Insight 1 but with no result. Finally changed the EGR and all was good again. But the Legend-infos are more worth here as the Insight 1 has a three pin EGR, the NSX/Legend only has two (not sure).
http://www.insightcentral.net/forum...on/16097-erg-plate-removal-cleaning-pics.html
EDIT: I've cleaned the passages on my Insight 1 but with no result. Finally changed the EGR and all was good again. But the Legend-infos are more worth here as the Insight 1 has a three pin EGR, the NSX/Legend only has two (not sure).
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My 91 has had a hesitation , occasionally, ever since I've owned it. Happens, maybe, once a year. Has done it once, since all hoses were replaced.
Just spoke with my local Acura parts guy. EGR Control Solenoid is on back order. He checked every dealership in the country and was unable to located one. I guess if I can't clean it, I'll post an ad here or look for one out of a Legend at my local salvage yard.
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It looks as is they don't think it to be a frequent part to replace or they had so many replacement...
It's quite a common part to replace in other Hondas.
I sincerely hope this resolves your issue. Hopefully you can update us when you find out.
Like I said previously, disconnecting the EGR seemed to help as the car seemed to run strong/better, but ultimately the hesitation was stronger/more significant.
I'm going to have a shop look over mine and suggest looking into the EGR.
After reading all of this I would check and confirm the TPS is working correctly. The ECU knowing where the throttle is and what manifold pressure is pivotal to properly controlling the fuel air ratio.
I presume a quick test would be to turn off TPS? Or maybe even disconnect it all together and see if that is the solution?
Throttle Position Sensor
Sorry, driver error, brain malfunction. :redface:
Have you checked your spark plug gap accurately?
Did you verify there was vacuum going to the solenoid from the CVC valve? How do you know it's the solenoid and not the CVC?
If you don't have a check engine light, then the system is most likely working. Hard to imagine the ECU never finding a good time to engage the EGR, as it usually happens when you accelerate at part throttle...many, many times during most drives. And if the ECU is trying to activate the EGR and the EGR really isn't getting vacuum, then you should have a check engine light due to lack of lift on the EGR valve. Consider tee-ing in a gauge to the EGR hose, and measure EGR vacuum while driving around.
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There's a description of the EGR system on page 11-128 in the SM. The ECU sets the lift of the EGR valve, the EGR reports the actual lift back to the ECU. The ECU compars both and sets the appropriate parameters for the engine.
When diagnosing the EGR on my Insight 1, there was no code stored in the ECU even though the engine was herky-jerky at part-throttle. It was fine at full throttle. The tests per SM didn't show a problem. The passages were cleaned. It was the worn potentiometer inside of the EGR that was giving the ECU wrong data of how much the lift of the EGR was. Wrong data to the ECU means wrong parameters set by ECU. A code is only set if the EGR doesn't work at all.
When diagnosing the EGR on my Insight 1, there was no code stored in the ECU even though the engine was herky-jerky at part-throttle. It was fine at full throttle. The tests per SM didn't show a problem. The passages were cleaned. It was the worn potentiometer inside of the EGR that was giving the ECU wrong data of how much the lift of the EGR was. Wrong data to the ECU means wrong parameters set by ECU. A code is only set if the EGR doesn't work at all.
My testing was a bust. Yesterday, I pulled the black emission box from my car, which contains the EGR Control Solenoid (ECS), MAP sensor, CVC etc. When I tested the ECS Thursday night, I didn't realize from the picture in the manual that the connector is shown upside down. So, when I applied +12V to what I thought was the ECS, I was actually testing one of these two sensors
The following picture shows the 6-pin connector rotated 180 degrees from its mounted position. I missed that on Thursday.
The 6-pin connector is tied to three components and not just the ECS. When I realized my mistake, I tested the ECS and it works perfectly. I guess I'm glad, but I'm no closer to a solution.
I agree that a CEL should appear when a system is not working properly, but unfortunately, systems can fail and not be detected by the ECU.
James
The following picture shows the 6-pin connector rotated 180 degrees from its mounted position. I missed that on Thursday.
The 6-pin connector is tied to three components and not just the ECS. When I realized my mistake, I tested the ECS and it works perfectly. I guess I'm glad, but I'm no closer to a solution.
I agree that a CEL should appear when a system is not working properly, but unfortunately, systems can fail and not be detected by the ECU.
James
