need help, don't know where to start
11-27-07, 11:22 PM
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need help, don't know where to start
Hi, I got a 1986 rx-7 n/a a couple months ago and it is in rough shape. I’m new to rotaries and I have limited experience with engines in general. I’m pretty much stumped, and I was hoping that someone might recognize these symptoms and be able to tell me what might be the likely causes or at least point me in the right direction before I go systematically rooting through each system to find the gremlin(s)
The most pronounced problem is that it severely lacks power - I’ve barely gotten it past 50 down hill at full open. The oil gets very gassy and I have to change it after only about 20 minutes of running and it eats gas like crazy. I don’t think it lacks compression, though, because It doesn’t spew any smoke when I let up on the throttle at speed, and when I crank it over to re-prime the fuel lines after it’s run out of gas it makes a soft wunk wunk wunk sound out of the tail pipes. It also doesn’t spew any white smoke and the coolant isn’t contaminated.
The engine also has this weird pulsing, high idle where it’ll pulse on, then drop down and pulse on again with about a 1 second interval between pulses. It usually goes up and down between 2500 and 3000 rpm when it’s been idling for a while. The other day I got it to idle between 1000 and 1500 rpm and I was going to try to set the idle speed with the air adjust screw to around 750 rpm so I could attempt to check the timing (I figured it was probably going to stall but it was worth a try anyway) but when I turned the screw nothing happened, except when I cranked it all the way out the engine started popping like crazy. I don’t know if this is a sign that the problem/one of the problems lies in the throttle body or if its just another symptom of whatever’s causing the weird idle. The engine also seems to have a similar sort of problem when it gets to 3500 rpm. If there’s any sort of load on it whatsoever, it’ll bounce between 3500 and 4000 rpm with about ½ second intervals. Sometimes it’ll climb past but usually it won’t and I’ll have to switch to a lower gear till I can get to the next down slope. I’ve heard that this has to do with bad battery grounding but maybe it’s related to the other problems.
Lastly, I don’t know how important this is but I installed a new throttle position sensor a few days ago to see if that would do any good, as the old one was way out of spec, and I adjusted it with an led checker lamp when the engine was sort of warm and it didn’t have a problem, but then I readjusted it with the engine at full operating temp and now its really hard to start it when it’s even the slightest bit warm.
Some or all of these problems could be connected, but the car was stored in a barn for ten years with mice for company, and I’ve already had to fix nawed-in-half electrical lines, so its very possible that this car is just dying from multiple afflictions at the same time. I don’t know if anyone will be able to glean a diagnosis from these symptoms and I don’t expect any miraculous solutions or anything, like I said, this is basically just a last ditch effort to avoid massive exploratory surgery, so any help would be greatly appreciated.
Thanks for your time.
-Smokermobile
p.s.
this is my first post, but i have found many answers on this site that have saved me alot of grief, so thanks for all the help so far.
The most pronounced problem is that it severely lacks power - I’ve barely gotten it past 50 down hill at full open. The oil gets very gassy and I have to change it after only about 20 minutes of running and it eats gas like crazy. I don’t think it lacks compression, though, because It doesn’t spew any smoke when I let up on the throttle at speed, and when I crank it over to re-prime the fuel lines after it’s run out of gas it makes a soft wunk wunk wunk sound out of the tail pipes. It also doesn’t spew any white smoke and the coolant isn’t contaminated.
The engine also has this weird pulsing, high idle where it’ll pulse on, then drop down and pulse on again with about a 1 second interval between pulses. It usually goes up and down between 2500 and 3000 rpm when it’s been idling for a while. The other day I got it to idle between 1000 and 1500 rpm and I was going to try to set the idle speed with the air adjust screw to around 750 rpm so I could attempt to check the timing (I figured it was probably going to stall but it was worth a try anyway) but when I turned the screw nothing happened, except when I cranked it all the way out the engine started popping like crazy. I don’t know if this is a sign that the problem/one of the problems lies in the throttle body or if its just another symptom of whatever’s causing the weird idle. The engine also seems to have a similar sort of problem when it gets to 3500 rpm. If there’s any sort of load on it whatsoever, it’ll bounce between 3500 and 4000 rpm with about ½ second intervals. Sometimes it’ll climb past but usually it won’t and I’ll have to switch to a lower gear till I can get to the next down slope. I’ve heard that this has to do with bad battery grounding but maybe it’s related to the other problems.
Lastly, I don’t know how important this is but I installed a new throttle position sensor a few days ago to see if that would do any good, as the old one was way out of spec, and I adjusted it with an led checker lamp when the engine was sort of warm and it didn’t have a problem, but then I readjusted it with the engine at full operating temp and now its really hard to start it when it’s even the slightest bit warm.
Some or all of these problems could be connected, but the car was stored in a barn for ten years with mice for company, and I’ve already had to fix nawed-in-half electrical lines, so its very possible that this car is just dying from multiple afflictions at the same time. I don’t know if anyone will be able to glean a diagnosis from these symptoms and I don’t expect any miraculous solutions or anything, like I said, this is basically just a last ditch effort to avoid massive exploratory surgery, so any help would be greatly appreciated.
Thanks for your time.
-Smokermobile
p.s.
this is my first post, but i have found many answers on this site that have saved me alot of grief, so thanks for all the help so far.
12-03-07, 12:55 AM
#3
massive exploratory surgery seems like your only option man, you've got a load of problems there. If mice have been chewing up the wiring for ten years I suggest rewiring the entire thing if you haven't already. Then bust out your multi meter, grab an FSM and go to town. Sounds like you've got your hands full.
12-03-07, 01:52 AM
#4
bouncing idle
Re-ground the engine bay for starters. Check for vacuum leaks, like cracked, broken, or not even connected lines. I found two or three vacuum lines not hooked up at all on my fc when i bought it. Putting the vacuum lines made my idle smooth finally, then I just searched on this forum on adjusting the Idle and TPS, so I could lower my idle to 760.
Oh yeah flush the coolant system while year at it, make sure theres no bubbles in the coolant system I've heard that can cause idle problems.
good luck man, especially if the mice have been eating for 10years on this....
heres a link for the how-to on adjusting idle an such. http://www.rotorwiki.com/index.php/TPS_Adjustment
Oh yeah flush the coolant system while year at it, make sure theres no bubbles in the coolant system I've heard that can cause idle problems.
good luck man, especially if the mice have been eating for 10years on this....
heres a link for the how-to on adjusting idle an such. http://www.rotorwiki.com/index.php/TPS_Adjustment
Last edited by SIDEWAYZE_FC; 12-03-07 at 02:05 AM. Reason: add tps adjustment link
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