Engine idle rough after a few months in HG replace

[PandaBear]

The same old girl again, 1997 Acura Integra with 252k miles, rebuild 3 months and 1500 miles ago.

History:

Head warp at 180k miles due to cooling issue, head resurfaced and gasket replaced. Ran fine till 250k miles and the radiator cap stuck closed, creating a vacuum in cooling system and warp the head again. Head resurfaced, new belts, new water pump installed.

Now:

The engine shakes worse over the span of a week and I found a bad "torque mount" like this. I replaced a leaking oil pan gasket, NTK upstream O2 sensor (it was white and looks like silicone poisoned due to the past 2 head gasket leak and has 100k miles on it), and cleaned the idle air control valve with non chlorinated brake cleaner.


Problem:

After resetting the ECU (disconnect battery for a few hours), the car would drive fine and idle fine on the road, actually runs very smooth as well just like a new car. BUT, it seems to have a cold start chatter the sound of piston slap at the first 1/2 second when I cold start the engine the first time. If I turn it off after 5 seconds and immediately start it again, it wouldn't have the cold start chatter. At warm start, once in a blue moon I would have some rough idle but no cold start chatter (idle dropped to about 500 and runs rough for a few seconds, revving it up to keep rpm higher for a few seconds seems to get rid of it), and finally yesterday, the rpm dropped so low in a warm idle that the engine "squeak" unless I rev it higher for a few seconds.

No coolant lost at all, both in the reservoir and the radiator.

What could it be? Could it be bad idle air control valve, coolant temp sensor (not sender as it seems to be warming up in the gauge fine), bad timing, timing belt skipped a teeth, or another head gasket?

 

[Fordtrucktexan]

First thing - don't go throwing parts at it and assume a blown hg or anything else.

It should have the Honda 1.8 "LS" motor. That's a pretty stout and simple to work on engine. Since it's a 97, have you tried pulling codes from the OBD2 port? It's located on the passenger side near the radio, just behind the dash.

If it's a blown hg, it could be blown in between the cylinders and not between a cylinder and cooling jacket, which is the most common.

Low idle can be caused by a number of items - blocked fuel filter, bad plugs and/or wires, or a faulty distributor. It is a bit uncommon for OEM Honda distributors to go bad though. Check to make sure the 10mm bolt that holds the distributor 'clocked' to the head hasn't shaken loose and thrown your timing off as well.

Just ideas off the top of my head without physically seeing the car run.

 

[Drew99GT]

I believe Brake cleaner can be bad for sensors/idle control valves. *perhaps* the brake cleaner harmed the idle air control valve or the TPS? Did the issues get worse after you used the brake clean on the IAC? Apparently throttle body cleaner is sensor safe.

Many older cars have a diagnostic for the IAC where you bridge to connectors in the diagnostic port and it puts the IAC in diagnostic mode and will raise the rpms to a specified level and after 5 seconds, return to normal.

I'd suspect the IAC. I'm having similar issue on my Corolla and the only way I've gotten rid of them is to take the IAC apart, fill the ports with CRC throttle body cleaner, and wiggle the IAC valve back and forth to free up the crud.

 

[Rand]

The IACV if its anything like the ones I've seen has a bare alum bore that can wear and get junked up, Many times cleaning isn't effective and you need to replace.

 

[PandaBear]

Originally Posted By: Fordtrucktexan
blocked fuel filter, bad plugs and/or wires, or a faulty distributor. It is a bit uncommon for OEM Honda distributors to go bad though. Check to make sure the 10mm bolt that holds the distributor 'clocked' to the head hasn't shaken loose and thrown your timing off as well.

Just ideas off the top of my head without physically seeing the car run.


I changed the fuel filter last year, plugs look fine and wires are new (I kept my old ones around and can put them back in to check tonight). Distributor coil was replaced at 180k, right after the 1st head gasket leak that gunk up the plugs and the misfire probably killed the coil. The bolt that hold the "alignment" of the distributor to the head seems to be stable.

Originally Posted By: Drew99GT
I believe Brake cleaner can be bad for sensors/idle control valves. *perhaps* the brake cleaner harmed the idle air control valve or the TPS? Did the issues get worse after you used the brake clean on the IAC? Apparently throttle body cleaner is sensor safe.

Many older cars have a diagnostic for the IAC where you bridge to connectors in the diagnostic port and it puts the IAC in diagnostic mode and will raise the rpms to a specified level and after 5 seconds, return to normal.

I'd suspect the IAC. I'm having similar issue on my Corolla and the only way I've gotten rid of them is to take the IAC apart, fill the ports with CRC throttle body cleaner, and wiggle the IAC valve back and forth to free up the crud.


Originally Posted By: Rand
The IACV if its anything like the ones I've seen has a bare alum bore that can wear and get junked up, Many times cleaning isn't effective and you need to replace.


I was stupid enough to do 2 work at the same time: cleaning IACV and replacing O2 sensor.

The one I have looks like this:

Prior to cleaning, the input port (the one with a metal screen) looks completely blocked. I was spraying to clean the screen as well as taking the screen out to clean the valve internal. I originally suspected the valve was flooded and cause the rough idle that would stall the engine right after, so I opened it up again and let it air out, as well as resetting the ECU to relearn the new O2 sensor. Afterward it holds idle without stalling, and the rough idle for a few seconds after start of the car seems to have improved (and local driving improves a lot).

 

[Chris142]

Vacuum in a cooling system killed a hg? I doubt it.

 

[Skid]

Have you adjusted the idle? Usually, you have to warm up the car fully, disconnect the plug to the IACV, and then adjust the idle screw. Then plug the IACV back in.

 

[The_Eric]

Is this the same car the mech botched the repair on and had to tow it back to re-repair once or twice?

 

[PandaBear]

Originally Posted By: The_Eric
Is this the same car the mech botched the repair on and had to tow it back to re-repair once or twice?


Yes.

Originally Posted By: Skid
Have you adjusted the idle? Usually, you have to warm up the car fully, disconnect the plug to the IACV, and then adjust the idle screw. Then plug the IACV back in.


I haven't adjusted idle, but I have replaced O2 sensor, cleaned IACV, and replaced leaking exhaust flange gaskets.

 

[The_Eric]

Originally Posted By: PandaBear
Originally Posted By: The_Eric
Is this the same car the mech botched the repair on and had to tow it back to re-repair once or twice?


Yes.

Originally Posted By: Skid
Have you adjusted the idle? Usually, you have to warm up the car fully, disconnect the plug to the IACV, and then adjust the idle screw. Then plug the IACV back in.


I haven't adjusted idle, but I have replaced O2 sensor, cleaned IACV, and replaced leaking exhaust flange gaskets.


Knowing the past history and not knowing much in the way of data, I think we'd be hard pressed effectively help you over the net.

I'd be pretty reluctant to go back to the mech that messed up the work the first couple of times- and didn't you say it was kind of a drive to get there? At any rate I think you should go see a local and respected shop and get their opinion, then if related to prior work, approach the other mech about some compensation.

 

[Merkava_4]

Head Gasket

 

[ltslimjim]

Does this engine have a fast idle valve as well as the IACV? Sometimes called the FITV.

I replaced the IACV in my 92 D15Z1, and it seemed to help with a low idle problem but that was prior to replacing the head-gasket which seems to have been the source of the low idling problem. I also replaced the manifold gaskets as well when the head was removed and could have indirectly fixed an IM leak but most likely the low coolant allowed air in the cooling system and created a problem with the IACV's function.

Note I did also have the high-rev with the IACV at times when it would rev up/down constantly in colder weather. So, I still think my IACV was flaky at best so not too concerned that I replaced it.

The car idled fine since then, but I was driving around with a busted igniter and cracked coil with no noticeable idle issue just 2 years ago.

Also, the ECU was not opening the EGR valve so it failed emissions that year initially. Replaced ECU. Rebuilt dizzy with Honda igniter and coil. All good right? 1 year later it started leaking oil internally. *facepalm*

I have since replaced dizzy with aftermarket new Rich-Porter TD-42U from Canada. A good quality!

You may want to check for intake vacuum leaks.

Since the HG job for my engine, I no longer have to worry about coolant getting low and ingesting air(therefore affecting the IACV's operation due to it having air in the system).

If you aren't losing coolant, have a good radiator cap, and have burped the system for air I'd suspect IACV is possible. What about the termostat? At full temp after the engine is heat soaked have you could check each cooling hose to see if they are both fairly hot to make sure the thermostat isn't stuck closed or you are running cold.

As someone else indicated the other possibility is the less-common cylinder-to-cylinder blown gasket. Why not do a leak down test so you can see if one cylinder is leaking into the neighboring cylinder?

EricTheCarGuy is a Honda/Acura guy that has a lot to say about the older Honda's and idling issues:









^Please give these vids a look. Hope this gives you some thoughts of what to look for.

 

[PandaBear]

Thanks guys. Haven't got time to investigate the issue because my wife gave birth to a daughter 5 weeks early with some minor issues, and 2 days prior to the birth I got a 2014 PriusV two for a great bargain (5000 off MSRP because it is a last year model) and is driving that around for the moment.

I did another ECU reset, and so far the idle has been better but not perfect. Previously I have done (or though I have done) an ECU reset by pulling the ECU fuse instead of disconnecting the battery terminal. This time with a battery terminal disconnect, the idle has been smoother and the idle seems to stay higher at around 800-1000rpm at the same scenario that previously would be misfiring at 500rpm (i.e. about the same 30 mins drive time then 20 mins idle time).

The mechanic offered to look at it but since he is far away, I asked him what I can check first. He said look for coolant lost (which is none) and valve clearance (only cylinder 1 has 1 intake and 1 exhaust valve that is 0.001" too tight). After adjusting the valve, nothing has changed. I also checked if timing belt has skipped any teeth but the pulley / cam positions are lined up spot on.

I did notice some exhaust leak at between the header's "A" and "B" flange. I'm not sure if this is a cause but I'd imagine if anything it would be misfiring all 4 cylinders instead of 3/4 only.