2nd Generation Specific 1986-1992 Discussion

Hesitation when cold

Old 01-27-2011, 12:26 AM
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Ok... haven't driven the car personally yet but my buddy has been feeding me info on the car I just bought. He says before it was "running temp" it would hesitate past 3k rpm. Basically unusable power after 3k.



His quote:

"Yes, kinda... it sputtered hard, and acted as if the rotors weren't getting fuel or something, a loud clanking noise came from the engine compartment. But it could've possibly made it to higher rpms, but with those noises, and that feeling, I wasn't gonna push it. But before I let off, I didn't feel as if the engine was hitting a rev limiter"



Also he says the car has basically NO torque what-so-ever low end... before 3k rpm. lol it's good times.



He said when it warmed up it was fine... any suggestions? The car is an '86 GXL.
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Old 01-27-2011, 01:58 AM
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Sounds like neither of you have driven a rotary-powered car much Welcome to the world of Rx7's.



Its not unusual that it doesnt have much torque until around 3k. Rotary engines generally lack low end torque but have most response at higher rpms. Generally, the car will hesitate and buck around a little bit at low engine speeds.



Second, you really shouldnt be "hitting the rev limiter" while the car is still cold lol... I mean thats really the case for any car in general, just common sense
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Old 01-27-2011, 02:12 AM
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Originally Posted by Justen View Post
Sounds like neither of you have driven a rotary-powered car much Welcome to the world of Rx7's.



Its not unusual that it doesnt have much torque until around 3k. Rotary engines generally lack low end torque but have most response at higher rpms. Generally, the car will hesitate and buck around a little bit at low engine speeds.



Second, you really shouldnt be "hitting the rev limiter" while the car is still cold lol... I mean thats really the case for any car in general, just common sense


Sorry I should elaborate. The low torque he's referring to is compared to his 88 n/a rx7 he has (stock). He says it's significantly lower torque.

I know not to push her hard at all until it warms up... but with as much torque loss as he's saying it has he said he can barely move it (all he was trying to do was move like 15 feet to park) at the 0-3000 rpm range. And after that range is when it was acting shitty. Says the car works fine after it warms up though...



Thinking maybe... water thermo sensor?
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Old 01-27-2011, 02:18 AM
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Hmm. Is it a stock GXL? ...any history of a rebuild?



Could be a compression issue when its cold, then as it warms up the seals seat a little better. Hows the idle?
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Old 01-27-2011, 02:28 AM
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Originally Posted by Justen View Post
Hmm. Is it a stock GXL? ...any history of a rebuild?



Could be a compression issue when its cold, then as it warms up the seals seat a little better. Hows the idle?


According to the guy I got it from it was rebuilt about 46,000 miles ago. Not stock... it has racing beat cat-back / headers. Straight pipe instead of cat. Cold air intake. supposedly a street port when it was rebuilt... but I have yet to confirm and if it was it could have been a shitty port job making the low rpm torque shitty. Fuel pump is hard wired in with a manual cutoff switch. HKS ignition.



Idle is fine... he says it idles a bit around 1200 though but it's an even idle... doesn't bounce.



Could be the compression thing. I DO plan to rebuild when I get home to her... just trying to figure out where these little headaches are coming from first.
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Old 01-27-2011, 02:58 AM
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Well, it may be a little unresponsive at low rpms because of the streetport (depending on how large it is), cold air intake, and the cat-less free flow exhaust... Especially on an N/A. Since you're letting the motor breath easier with those mods, you're also taking away a slight amount of back-pressure. This might make low end bucking a little worse. I noticed a slight drop in low end response when I did my streetport, TB port, emissions removal, and cat-delete on my turbo2.



Idle seems a bit high, though. Should be around 750-1000rpm.

When you get it home, check it out visually. Maybe try to lower the idle to 1k rpm and see if she bounces



You probably won't know the condition for sure until you drive it yourself
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Old 01-27-2011, 03:06 AM
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Yeah it's true I won't know until I driver her myself... just trying to make a list of everything wrong with possible solutions before I get back.



I know the idle is a bit high... just hoping that a quick tps fix.



The low low end torque wasn't the biggest issue I was trying to find out on this one though. I know many things that THAT could be... but mainly I was trying to figure out this running like **** when cold thing. Appreciate all the help so far though.

But do you think a water thermo sensor could be a likely culperate for that one?
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Old 01-27-2011, 03:43 AM
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Water thermo seems to make sense I think... possibly making the car run just a bit tooo rich and when the aux ports open the AFR is just too low to handle and bogs down.
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Old 01-29-2011, 01:15 AM
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Grounds are a good starting point
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Old 01-29-2011, 03:09 PM
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Originally Posted by sixstar View Post
Water thermo seems to make sense I think... possibly making the car run just a bit tooo rich and when the aux ports open the AFR is just too low to handle and bogs down.


Its possible. When the lead on my thermo sensor wire snapped, my car just ran like **** all the time because the sensor circuit just went into closed loop "limp mode". Ran the codes, found the snapped wire, repaired it. Fixed.

BUT since your problem seems to fade in and out, its possible that the actual sensor is bad.



***I highly recommend you make yourself a code reader though, before anything else. It will help you narrow things down.



http://www.teamfc3s.org/info/article...tion%20Picture
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