hopefully my last post for a while
08-10-19, 01:18 PM
#1
hopefully my last post for a while
Hello all, I have an 86 gxl that I put another s4 engine into. I got it together and running except it cranks for a loong time before roughly starting. once started the idle is pretty high like 1500 but after the thermowax melts it still idles/surges around 1100. if I press the gas it bogs down slightly before picking up after some time. I really just want the car to be done because I have been working at it for almost a year and I'm losing the drive for this project even though I REALLY want an fc.
08-11-19, 11:22 AM
#2
Senior Member
Slash,
the factory manuals for your car and engine can be found at either foxed.ca, or rotaryheads.com. You will be looking for the section titled fuel and emissions for your year and engine type. First items to check - vacuum leaks. If that's not it, there is a troubleshooting chart in the manual that tells you what priority certain items are in causing engine problems, and then gives you a method to check them. Please try this method, and if it gives you some more information, let us know and we can try to help further.
the factory manuals for your car and engine can be found at either foxed.ca, or rotaryheads.com. You will be looking for the section titled fuel and emissions for your year and engine type. First items to check - vacuum leaks. If that's not it, there is a troubleshooting chart in the manual that tells you what priority certain items are in causing engine problems, and then gives you a method to check them. Please try this method, and if it gives you some more information, let us know and we can try to help further.
08-14-19, 04:26 PM
#4
It seems like this gets missed a lot - check/adjust your TPS. It can throw off a lot of things if its out of alignment or just plain bad. These things are getting old, and I've seen plenty of bad TPS's out there. There's a check procedure in the FSM. Also move it by hand to make sure there are no dead spots. Quick search also brought this up: https://www.rx7club.com/2nd-generati...-101-a-235007/ Make sure to check post #4 from Aaron Cake. I'm sure there's many other threads as well.
Once that's set, it is usually from a vac leak, and there are a lot of things on a car this age to cause that. One trick is to put a vac hose on a propane torch, open the valve on it, and run the hose all around the intake. If it smooths out, you found your vacuum leak.
If that's not it I would look at cleaning the fuel injectors, especially if they were sitting for a while. Honestly, I would look at that anyway with ones that have been sitting for a while. I don't know who the preferred place for that is anymore, but I'm sure a quick search will give you an answer if you want to go that route.
As for the idle, if its still bad after adjusting the TPS, its probably just a mis-adjusted idle screw. Once you get the idle smoothed out, you can look at setting that.
A final note - I've been there many times as a project drug on. Hang in there, it will all come together! Most importantly - don't rush and take short cuts. I know its frustrating and you really want it running, but take it from hard experience - you will be even more frustrated if you end up having to rebuild the engine because you sped through things to get it finished and screwed something up. Its happened on 2 NA motors and 3 turbo motors for me, ranging from tearing down because it overheated after plugging a coolant nipple port with a vacuum cap I had laying around instead of plugging it the correct way, all the way to replacing 1000's of dollars in engine parts because I got into boost before I fixed my tune.
Once that's set, it is usually from a vac leak, and there are a lot of things on a car this age to cause that. One trick is to put a vac hose on a propane torch, open the valve on it, and run the hose all around the intake. If it smooths out, you found your vacuum leak.
If that's not it I would look at cleaning the fuel injectors, especially if they were sitting for a while. Honestly, I would look at that anyway with ones that have been sitting for a while. I don't know who the preferred place for that is anymore, but I'm sure a quick search will give you an answer if you want to go that route.
As for the idle, if its still bad after adjusting the TPS, its probably just a mis-adjusted idle screw. Once you get the idle smoothed out, you can look at setting that.
A final note - I've been there many times as a project drug on. Hang in there, it will all come together! Most importantly - don't rush and take short cuts. I know its frustrating and you really want it running, but take it from hard experience - you will be even more frustrated if you end up having to rebuild the engine because you sped through things to get it finished and screwed something up. Its happened on 2 NA motors and 3 turbo motors for me, ranging from tearing down because it overheated after plugging a coolant nipple port with a vacuum cap I had laying around instead of plugging it the correct way, all the way to replacing 1000's of dollars in engine parts because I got into boost before I fixed my tune.
08-15-19, 12:42 PM
#5
I have checked for vac leaks and didn't find any. I think I adjusted my tps properly but I never checked for dead spots soIi will try that. I will also try to adjust it again and look into the injectors. I was just beginning to think it was the injectors so my plan was to try and run some injector cleaner through it with my finger crossed. Thank you for the inspiration about projects my goal was to get it ready before I went back to college but I might have to settle for a week or two after.
08-16-19, 12:31 PM
#6
so last night I confirmed that the tps was adjusted properly and checked for dead spots. everything looked good. idle still surges so I bought a bunch of silicone vacuum lines to redo the whole system and while I'm at it I will inspect injectors.
08-16-19, 12:33 PM
#7
Senior Member
I would check the system for leaks using compressed air. Sometimes it will let you know of any leaks you can't find with a visual inspection. One main culprit for me was the rubber fuel injector grommets.
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08-16-19, 12:40 PM
#8
A good way to check for invisible cracks on the plastic intake hoses is to pour a little soapy water on them then pressurize them somehow, by firing the car up or pyroman's compressor trick. . If there's a crack you'll see the bubbles.
Hopefully it's something as simple as that.
Hopefully it's something as simple as that.
08-16-19, 01:25 PM
#9
Senior Member
If you use compressed air, 20psi should be more than adequate pressure. Make sure to disconnect your MAP sensor first so that you don't damage it during the testing.
08-29-19, 12:56 PM
#19
I don't have any cats. only thing is I have a leak in the exaust but if anyting that should give me more power cause more flow. my ports are wired open so I'm not looking for the low end but even in the top end, it seems pretty pitiful. is it possible when I push the gas pedal it isn't getting to WOT?
08-30-19, 10:09 AM
#20
I don't have any cats. only thing is I have a leak in the exaust but if anyting that should give me more power cause more flow. my ports are wired open so I'm not looking for the low end but even in the top end, it seems pretty pitiful. is it possible when I push the gas pedal it isn't getting to WOT?
09-03-19, 10:05 AM
#21
So I got the plates and drove the car around a bunch this weekend and learned A lot. It doesnt have low power I just wasn't driving in the powerband. The hard start issue was due to a bad battery and me not letting the fuel pump run enough when starting. I still didnt fix any vac lines yet so the idle still surges and i think my oil pressure gauge is reading wrong because I dont think I have the little black condenser. Thankyou all for your help and if I have any other questions I'll be sure to ask. Next is installing a coolant temp gauge and taking it for some long drives.
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