Hey guys, things have been going great with my build thanks to you all. It is running really good, and most of the issues/CEL lights have been squashed.
When I accelerate at a constant rate, as it reaches about (almost exactly) 5k RPM the throttle hesitates for a second. It is nothing crazy, some people may not even notice it, but I definitely do. After about half a second it goes away and continues to accelerate normally. If I am flooring it, the throttle is smooth all the way through and vtec engages normally.
I just finished installing a walboro fuel pump (pain in the ass!) however that did not fix the problem. It does seem to run “better” but the hesitation is still there.
I do have a what I think is a vacuum leak, somewhere around the brake booster. I have not been able to track it down yet. But I have a hunting idle at times and that is on my laundry list. Related?
I have replaced the ignition coil, distributor cap and rotor, spark plug wires and plugs. Also a new o2 sensor. Timing was set and then just recently checked to make sure it is dead on.
This is a b17 in a 91 rs. Hopefully I can nail this down.
Oh and as for CELs I had a 43 and 41 which turned out to be at least partially related to a bad o2 sensor.
That’s a really tough one. Without driving the car and experiencing it it’s always hard to say and it sounds like you’ve already looked into the obvious first places to start (timing, ignition components…). Have you replaced the fuel filter? Unlikely that’s it, but worth looking into.
I would make sure to fix the other issues first, make sure there are no CEL’s, idle is stable and your vacuum leaks are gone. Then look into the hesitation more.
What ECU are you running? Is it stock, chipped? I assume the car has not been professionally tuned? Is the flat spot consistent or is it different sometimes (more or less hesitation, different rpm, different during different atmospheric conditions…etc)?
The “flat spot” is extremely consistant, seems to be the exact rpm every time. lately I have simply avoided the area by shifting earlier. The ecu is stock from the 92 gsr, and no it has not been tuned in any way. Still trying to iron out these issues and take it in to get it BARd.
I think you are right about fixing the other stuff. CEL’s are cleared for now, as long as my wiring to the O2 sensor holds up. But the vacuum leak I just do not know where to start. I believe I can hear it near the brake booster, but I would like to narrow it down more before buying hoses.
I just put in a gsr cluster and I love it. Much easier to see what rpm it is at. If I have to take my cluster out one more time I am going to lose my mind (or my hand).
Anyway I will work on that vacuum leak and report back, thanks again
I wouldn’t expect a vacuum leak to give you a hunting idle, I’d expect it to just give you a raised idle. Unless the leak is intermittent and inconsistent. Hunting idle usually indicates to me that there’s something wrong with:
[QUOTE=Colin;2330225]I wouldn’t expect a vacuum leak to give you a hunting idle, I’d expect it to just give you a raised idle. Unless the leak is intermittent and inconsistent. Hunting idle usually indicates to me that there’s something wrong with:
coolant level and/or air in the cooling system
IACV
FITV
Throttle body
Incorrect timing
Issues with the ecu tuning[/QUOTE]
I removed and cleaned the IACV, twice
We opened the FITV and tightened that down
Throttle body removed and cleaned
Timing was set and then checked on separate occasion
I have had thoughts that the coolant has air in it. I replaced the radiator during the swap and have never bled the system with a funnel/bleeder. So maybe I will start with that. But ya the idle comes and goes sometimes it idles perfectly, then out of nowhere it bounces from about 500-900 rpm. Sometimes when I brake it drops almost to around 250 then surges back up. I don’t know, my time is getting short, gotta smog this thing in a month and a half. Might have to just take it in somewhere to sort everything out $$$$$$$$$$$ :worry:
Try using the bleed bolt for the coolant and then “burp” the system by letting it run with the radiator cap off. Let it run and heat up to operating temp (fans should kick on and you should see the fluid level fall and rise as the thermostat opens/closes). Add more coolant as needed while burping it. This technique has worked well for me.
I agree with Colin that a Vac leak is unlikely, but a can of something like brake cleaner sprayed (carefully) around suspect areas can help pinpoint the leak if you have one. Also just cause you cleaned the IAC, doesn’t mean it’s now good.
Also I wonder a little about your injectors, maybe one or more is a bit gummed up.
Thanks for the reply, sorry it has been a while. The injectors could be the problem? Is there a place you could recommend to get them cleaned out? Or is it better just to replace them? It is something I thought of doing, since it occurred to me I may not be getting enough fuel.
Also, when cleaning out the IACV I did not warm the car up first, so I don’t believe it was cleaned out all the way. (I believe when warmed up the valve opens and then can be cleaned.?)
Anyway I’m just trying to get this cleaned up and buttoned down so I can attempt to get it smogged (yikes)
I’m not sure about the IACV, but I’m pretty sure you should be fine with the valve closed. It relies on signals from the ECU as well as temp from the coolant that flows through it so I don’t know if you can even warm it up and have it open without the electrical inputs from the ECU. Either way, cleaning it should work well enough with the valve still closed - unless it’s seized of course. But I can’t remember ever hearing of that happening.
RC Engineering is the go-to place for injector cleaning. And I’d definitely clean instead of buy new, buying new will be expensive. I had mine cleaned by Cruzin Performance and thought their service was great and was cheaper than RC.
Awesome, thanks Colin I will check those places out.
I actually have something to report, progress for once. Finally got my mobile mechanic out and he was able to fix the idle issue. I was blown away, but it was the Throttle Position Sensor. He said it was “way off”. Anyway for the first time maybe ever, it idles steady. The “flat spot” in throttle is still there, so I will look in to having the injectors cleaned.
My buddy was also able to determine two of the wires on my o2 were flipped around, causing my code 43 and code 1. So those are cleared for now. Which is great because I have like less than 2 weeks to get smogged :shock:
After installing the Ecu I bought from a member here, the symptom seems to have gone away. This is the California p61L00 I believe. So possible the Ecu was bad? Any way to test or repair them? So I’ll keep driving it and seeing if it happens again. Seems smooth all the way through so far
But at least it seems to be fixed :dance: