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As the title suggests, I’m having an idle issue that isn’t exactly typical. I have a 1996 integra ls with a stock motor. It has a new distributor and alternator. The car first had a slight occasional surge from 1k-1.2k. It was throwing codes for the IAC, crank position sensor, and evap purge flow. I had the car serviced and had rear main seal, timing belt, water pump, oil pan gasket, and clutch all replaced. After I got it back I replaced both the IAC and evap purge solenoid. The car began surging up and down between 1k-2k non stop unless I’m driving and will continue if I take it out of gear. Also aggressively bucks the car back and forth if I drive at really low speeds. Now the car is only throwing codes for crank position sensor, and another one for P1508. I know that code can be for wiring but also about anything involving the intake. I just need some opinions on some strong possibilities and I can’t find anything specific to this scenario in the forums. Any input will help. Thanks all
You have to make sure you put on the correct IACV. If your car is manual and you put on the IACV for an auto or an OBD1 car, then you'll get that kind of crazy surging your talking about. Bad/incorrect IACVs can also cause bucking at low speeds.
I just need some opinions on some strong possibilities and I can’t find anything specific to this scenario in the forums. Any input will help. Thanks all
Check for vacuum leaks, The symptoms you describe (apart from the CEL codes) lean towards a major leak somewhere on the manifold. Check all the hoses, especially the ones on the back of the manifold.
IAC stuck open? Disconnect and see if you get any change. Get the shop manual for your car and go through the test procedures for the IAC. Usually involves covering a hole in the manifold with your finger.
Idle set too high. If possible, check and set idle according to the shop manual.
I know it scares a lot of people for some reason, but I would also do a leakdown test (look it up) to verify the integrity of my combustion chamber, due to the multiple CELs.
A bouncing/surging idle is almost always caused by air/fuel delivery in the throttle body or intake manifold areas.
You have to make sure you put on the correct IACV. If your car is manual and you put on the IACV for an auto or an OBD1 car, then you'll get that kind of crazy surging your talking about. Bad/incorrect IACVs can also cause bucking at low speeds.
well the counterpart for an automatic would be a FITV wouldn’t it? And from what I know the part is completely different in design. I got a identical replacement piece for mine
Check for vacuum leaks, The symptoms you describe (apart from the CEL codes) lean towards a major leak somewhere on the manifold. Check all the hoses, especially the ones on the back of the manifold.
IAC stuck open? Disconnect and see if you get any change. Get the shop manual for your car and go through the test procedures for the IAC. Usually involves covering a hole in the manifold with your finger.
Idle set too high. If possible, check and set idle according to the shop manual.
I know it scares a lot of people for some reason, but I would also do a leakdown test (look it up) to verify the integrity of my combustion chamber, due to the multiple CELs.
A bouncing/surging idle is almost always caused by air/fuel delivery in the throttle body or intake manifold areas.
So quick update everyone. First, I’ve heard of certain electrical parts having to be “calibrated”, so I was wandering what the chances are that my new IACV is bad. I put the old one back on and although the idle is still funky, all I had to do was tighten the idle control screw on the throttle body (lowering the idle) and it helped stabalize the idle and doing that didn’t help with the new part. It’s still unpredictable but for the most part it is less likely to surge so intensely when it does. I can’t be sure if my new IACV is bad (it might just not be up to oem specs) but I’m convinced there is something else wrong because the engine will do weird things with the idle with the new part and the old one when. I also have weird smoke or steam coming from behind the intake. Seems like it’s coming from one of the coolant hoses connecting to the IACV. Also smoke comes from what seems to be the exhaust headers when I rev while warm. Not sure if those are the only leaks you were talking about. Im gonna change the intake manifold and exhaust manifold gaskets to try to plug up any air leaks. Also gonna see if I can get an oem Honda IACV instead of aftermarket. If you have anymore suggestions then have at it please
I actually just found something else out completely by chance. It sounds ridiculous but it’s worth investigating and I’m not too sure but it could have something to do with my current problem. I just found that when I am at a stop in my car is idling, it idles higher the more I pump my brakes and then will fluctuate and go back to a normal idle when I stop. I can repeat this over and over
I could be wrong but I believe that pressing on the brake like that, producing the effect that you are getting, is just more evidence that you have some kind of leak around the intake manifold.
I am probably just gonna get a new brake booster and inspect everything in and around the old one
You've got a vacuum leak somewhere. The brake booster has a big vacuum hose on it. Idle surging is usually a vacuum leak or possibly low coolant. I'd inspect/change vacuum hoses before I'd change a brake booster.
I had a similar problem a while back on my '94 LS. When I first started the car it would surge like you described. Once it warmed up though mine would go back to a more normal, consistent idle. I had to tighten a piece in the FITV and it worked fine afterwards. Wasn't too difficult to get to and didn't need to buy any new parts.
Symptoms sound a little different but still a simple thing to look into before buying anything.
So a quick update to the thread: I’ve been playing around with the idle screw on the throttle body and the idle valves that I have (switching them back and forth) and I changed the whole intake to a new cold air one. I checked my plugs a little bit ago and all except one look good. Well now for some reason the motor went from dying if it idles too long, to dying once it’s warm. It’s fine on start up but as I drive the car and it warms up, once I come to a stop it will begin to slowly drop down the rev range and come to a halt unless I give it gas or hit the brake pedal (I said previously the engine revs a small amount when I play with the brake pedal).
Im taking the car in for a full engine rebuild to prep for boost especially with a possible spun bearing. If anyone has any info on the sudden warm engine death then let me know. Otherwise I’ll keep the thread updated afterwards
I’ve been playing around with the idle screw on the throttle body
This is not how you set your idle, and you can't set your idle with a vacuum leak present. Plug the vacuum hose to the brake booster, if you want to rule that out.
From my experience, this is something that should be fixed asap.
My '91 DA started doing this kind of surging at around 290,000 kms, and I didn't do anything about it (old car, not worth it). A few weeks later the engine started making a loud banging sound. then a few days later seized completely.
Mechanic took the engine apart and told me it was something to do with the water pump and timing belt. (But it looks like OP has already looked at that).
These are the pics of the dead engine and part responsible for it.
I don't think the thermostat was working on this engine properly. The engine temp gauge would never rise more than a millimeter, no matter what the outside temp or length of driving. Always sits at C. Therefore I think the engine was getting incorrect temp readings which probably accelerated the cooling system/water pump problems.
I don't think the thermostat was working on this engine properly. The engine temp gauge would never rise more than a millimeter, no matter what the outside temp or length of driving. Always sits at C. Therefore I think the engine was getting incorrect temp readings which probably accelerated the cooling system/water pump problems.
No your water pump failed then seized and broke. Usually when you have temp issues like you had it usually indicates your water pump has failed!
02-26-2019, 09:14 PM
B18b1 Crazy Surging
