| Go back to previous topic | | Forum name | Turbo/Nitrous Tech | | Topic subject | My engine "hesitates" under boost...any theories? | | Topic URL | https://forums.2gnt.com/dcboard.php?az=show_topic&forum=i8&topic_id=2166 |
2166, My engine "hesitates" under boost...any theories? Posted by fly1, Feb-27-01 03:19 PM
* I have HRC stage 2, sidemount I/C, 190 lph intank fuel pump.
I just got my car back and it's not really running smoothly.
Scenario 1: Up to about 3K rpm everything sounds good, air/fuel is normal. From about 3500 rpm to 4500 rpm the car seems to "hesitate", air/fuel shows "lean" for a a couple of seconds, then jumps to "stoic" or "rich" just right before I shift to 2nd gear. Same thing happens in 2nd to third. However, this problem seems to be intermitten.
Scenario 2: On the freeway--say in third gear--when under full boost 7-8 psi, the car again hesitates a little before kicking in. Even when the turbo kicks in, it's not very strong--almost hesitating. What worries me the most is that when boost hits 8-9 psi, it sometimes jumps back to 5-6 psi; at the same time, the air/fuel meter shows lean for at least 2 seconds before going stoic or reach. I'm afraid of detination, so I won't be pushing it for a while.
Do you guys have any idea as to what's happening hear? Has any of you experienced this problem? I know of "turbo lag" but that doesn't seem to be the problem here. Is it because I need to go to a higher pressure fuel pump--like a 255 lph? Any suggestion or opinion will help.
Thanks, Fly1 http://fastgs.homestead.com/fastgs.html
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2167, RE: My engine "hesitates" under boost...any theories? Posted by JasonESi_T, Feb-27-01 04:04 PM
Two things...
One, this board has already made it kind of an issue that an upgraded in-tank fuel pump is only a marginal solution to meeting your fuel needs for any boost above 7 psi or so maybe. So please keep that in mind before you start boosting higher. That's with the 255 walbro in mind as well. The 190 is of coruse that much more limited.
Second, sounds as if youre experienceing fuel cut. Does the hesitation occur right at the onset of boost? If so, then establich your fuel mapper wires to a greater degree. This problem is VERY COMMON. wrap your fuel mapper wires around those map sensor wires no less than 3 or 4 times in my mind, and then solder. What year is your car (may not matter)?
If you've elminated these problems, get a EGT guage as well. An A/F meter may not be enough to establish that youre running lean. You should assume that you are to be on the safe side. Don't boost in any long gear pulls. Could be dangerous until you have your problem figured out.
Jason 98' Eagle Talon ESi-T Mitsu Super 16g Turbo(HRC)
http://springfielddsm.homestead.com/JasonsPics.html
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2168, RE: My engine "hesitates" under boost...any theories? Posted by fly1, Feb-27-01 11:37 PM
>Second, sounds as if youre experienceing >fuel cut. Does the >hesitation occur right at the >onset of boost? If >so, then establich your fuel >mapper wires to a greater >degree. This problem is >VERY COMMON. wrap your >fuel mapper wires around those >map sensor wires no less >than 3 or 4 times >in my mind, and then >solder. What year is >your car (may not matter)?
Yes, this hesitation occurs a little after some boost all the way up to full boost (7-9 psi). Hmmm, I'll try wrapping the fuel mapper wires. Oh, if it matters, my car is a 1998 GS.
Has anyone done the fuelpump rewire? Did that help to increase fuel pressure? Also, since most of you has already upgraded or have the Walbro 255 lph pump--and it's still not putting out enough fuel pressure--does that only apply to running the stock injectors?
If I were to go to bigger injectors--not necessarily to HRC's stage 2--i.e. 440's or even 500's and use a S-AFC to run it, will that setup work? I think some of you are using similar setups, right?
Jason, thanks for the quick response.
Fly1 http://fastgs.homestead.com/fastgs.html
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2169, RE: My engine "hesitates" under boost...any theories? Posted by 96NOS_Eclipse, Feb-28-01 12:29 AM
If you have already checked all of the above, try your plugs and wires even if they look good, try swapping them for some you are sure work.
Michelle 96 Eclipse Base Model Best 14.6@93 w/60 shot

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2170, RE: My engine "hesitates" under boost...any theories? Posted by HRC, Feb-28-01 01:27 AM
I am hoping you installed our inline pump as provided with the turbosystem. No further pumps should be needed if this is the case.
I agree with Jason and Michelle. Check those areas over, and be sure to also consult the Troubleshooting Guide that came with your system. If you need further assistance, call my Tech Support line: 630-801-9065, open from 1-5PM CST M-F (except this Friday, as I will be out of town at a race in Florida. Ahh, sunshine....I am sick of cold, gloomy Illinois winter days!)
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2171, RE: My engine "hesitates" under boost...any theories? Posted by immigrantRyder, Feb-28-01 03:34 AM
What do you mean by "wrapping" the wires around the black box? I just got a used HRC stage 1 and am in the process of installing it. Help a brother out!
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2172, RE: My engine "hesitates" under boost...any theories? Posted by 95ESi, Feb-28-01 03:38 AM
it means you want to make a goood connection to the wires you are attaching to.
either you can splice into it (cut and solder or wrap it around)
l e o n
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2173, RE: My engine "hesitates" under boost...any theories? Posted by JasonESi_T, Feb-28-01 12:33 PM
That's right. I mean to wrap, wrap, wrap, wrap, 3 or 4 times AROUND THE MAP SENSOR WIRES. Re-read my post. I never said to wrap around a black box??? It's so important to establish a good connection here, or you will experience fuel cut. Originally, I had only spliced into this wire once and then soldered. IT WAS NOT ENOUGH. It worked like a charm though after the thorough wrap technique.
Good luck! :-)
Jason 98' Eagle Talon ESi-T Mitsu Super 16g Turbo(HRC)
http://springfielddsm.homestead.com/JasonsPics.html
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2174, RE: My engine "hesitates" under boost...any theories? Posted by BoostnRS, Feb-28-01 06:02 PM
Dude... just change your spark plugs !!! thats all it is.. Get yourself some new NGK's and boost away !!
Good luck !

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2175, RE: My engine "hesitates" under boost...any theories? Posted by fly1, Mar-06-01 09:02 AM
Well guys, I used everyones' advices, and my car ran a little smoother but, it didn't solve the hesitation/miss problem. When I tried to reset my AEM cam gears, I noticed the three hex key screws holding the cam gears were LOOSE! The shop that replaced my timing belt must have forgotten to tighten it or something. Basically, in between shifts, the intake cam gear could've shifted back and forth a little.
My concern now is--will that affect anything? I'm afraid that it could really damage my engine. I drove it around town for about 450 miles like that.
I appreciate all of your opinions and advices.
Later, fly1 http://fastgs.homestead.com/fastgs.html
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2176, RE: My engine "hesitates" under boost...any theories? Posted by BoostnRS, Mar-06-01 09:32 AM
Good to hear you discovered your problem ! About the damage part..just as long as its fixed now, and there are no problems, you should be cool. Having loose cam gears like that is very dangerous though.
Good luck !

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