Effing intake pop is back, hook up a vacuum gauge and the needle steadily drops 1 in hg with a rythym. Like looking at a watch. Thinking one of the intake valves is too tight leaving a slight gap but they are all in spec with the engine cold. Since everything expands when warm, would it be better to check it that way?
Valve adjustment, engine hot or cold?
- Thread starter jimtash
- Start date
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JRA2000TL
The Complainer
What???? Are you sure when you re-adjusted your timing that you didn't over-adjust it? Seems to me from your previous posts that the popping sound only started when you did that 2nd adjustment to the timing belt.
I still have not had time to address my timing belt whine, but a back-fire or popping sound would indicate that something might be off-time....at least I would think.
I still have not had time to address my timing belt whine, but a back-fire or popping sound would indicate that something might be off-time....at least I would think.
I thought so too but I redid it. It's in time. Thing is when the engine is cold, it runs normally. The popping starts roughly about 5 minutes idling and increases with frequency as the car gets hotter. Can't get it to backfire but it is popping.
Ishodu
SHO Member
Do you have a plug thats cracked?
New plugs. Haven't even been driven on the road. New wires as well. Been noticing hard starts after warm up. Have to press the gas pedal sometimes to get it started? The thing has 3.2 injectors on it (it's a 3.2 MTX) but that only cropped up recently. You don't supposes the CKP is at fault and acting up when hot?
Got the valve covers off and set it to TDC. Cam holder tool slips right on both pairs of cams. It's in time.
Intakes check out at 0.008.
Exhaust is 0.012.
Got the valve covers off and set it to TDC. Cam holder tool slips right on both pairs of cams. It's in time.
Intakes check out at 0.008.
Exhaust is 0.012.
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It tops off at 21 in HG then drops to 20 in a steady rhythmic pulse. Like clockwork. 21, 20, 21, 20. Engine vibrates because of it. When I open the IMRC at idle, the needle moves in a much larger range and with more frequency. Weird. These problems plagued the other engine as well. All the sensors from that engine are on this one. And from what I've been seeing, the intake pop get more frequent as the engine warms up. Does it with the MAF disconnected, doesn't matter.
Another problem is the idle quality when the fan comes on is poor. Sounds as if it has a miss and the idle gets lopey. Almost as if it has a high lift cam in it. And when the fan shuts off, the idle never regains consistency in it. Instead of a purr in the exhaust, it would again be lopey. I took care of that by raising the idle screw on the TB slightly.
The valvetrain is in good order and mechanical timing is good. Either a fuel or ECU timing issue. I'm using the 3.2L injectors but it's not tuned for them. Yet the other engine had the pink injectors and it still popped on me.
These are the cams at TDC:
Another problem is the idle quality when the fan comes on is poor. Sounds as if it has a miss and the idle gets lopey. Almost as if it has a high lift cam in it. And when the fan shuts off, the idle never regains consistency in it. Instead of a purr in the exhaust, it would again be lopey. I took care of that by raising the idle screw on the TB slightly.
The valvetrain is in good order and mechanical timing is good. Either a fuel or ECU timing issue. I'm using the 3.2L injectors but it's not tuned for them. Yet the other engine had the pink injectors and it still popped on me.
These are the cams at TDC:
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Ran it without the spout connectors and nothing changed. Took the ECT connector off and it subdued the popping noise considerably. Looks like it's malfunctioning and leaning out the fuel mixture. Vacuum gauge still does the same though.
gmail
Well-Known Member
It tops off at 21 in HG then drops to 20 in a steady rhythmic pulse. Like clockwork. 21, 20, 21, 20. Engine vibrates because of it. When I open the IMRC at idle, the needle moves in a much larger range and with more frequency. Weird. These problems plagued the other engine as well. All the sensors from that engine are on this one. And from what I've been seeing, the intake pop get more frequent as the engine warms up. Does it with the MAF disconnected, doesn't matter.
Another problem is the idle quality when the fan comes on is poor. Sounds as if it has a miss and the idle gets lopey. Almost as if it has a high lift cam in it. And when the fan shuts off, the idle never regains consistency in it. Instead of a purr in the exhaust, it would again be lopey. I took care of that by raising the idle screw on the TB slightly.
The valvetrain is in good order and mechanical timing is good. Either a fuel or ECU timing issue. I'm using the 3.2L injectors but it's not tuned for them. Yet the other engine had the pink injectors and it still popped on me.
These are the cams at TDC:
nice clean engine
No stored codes. No codes while running. Just connected the battery because of taking the timing covers off and making sure the timing is in sync.
Gauge needle shows a constant steady rhythm. At first I thought one of the valves wasn't closing but the way the needle drops, it as if though something is simply turning on and off.
It mimics scenario number 3 in the link except the drop is from 21 in hg to 20.
http://www.secondchancegarage.com/public/186.cfm
Thanks for the complement. The heads used to look like this:
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93markVIII
SHO Member
because all of a sudden the computer has absolutely no idea how much air is entering the engine?
gmail
Well-Known Member
exactly.... roughly 80% of the computers info comes from the maf... how much air is coming in is very vital to how to how much fuel to supply
Did a search here and this is what came up:
http://www.shoforum.com/showthread.php?t=97330&highlight=engine+dies+maf+unplugged
And just like I'm thinking what is wrong with my car, the crank sensor is being affected by heat and giving off false readings causing all sorts of headaches.
http://www.shoforum.com/showthread.php?t=97330&highlight=engine+dies+maf+unplugged
And just like I'm thinking what is wrong with my car, the crank sensor is being affected by heat and giving off false readings causing all sorts of headaches.
SHOtime2511
CGP
You are over thinking this problem.
Start with a simple check for vac leaks.
Start with a simple check for vac leaks.
JRA2000TL
The Complainer
Meh, come to think of of it, I had a horrible vacuum leak the last time I did some top-end work on my 89. I think it even had a popping sound like you describe. I removed and reinstalled the intake. I want to say I had a pinched line sitting between the runners and the engine, causing a massive vacuum leak.
As stated above, you have a vacuum leak. Before you bolt everything down, do the following: 1. obviously make sure all your little vacuum lines are connected (rear of intake, and the 2 "canister" looking thingys at the runners--I think there are 2). 2. Seat the intake and "rock" it back and forth to make sure it's "seated" dead-nuts on. 3. If it's flush, bolt it down.
I am an amateur at this, and I've had my share of removing and reinstalling crap more than once. If your timing is set correctly and your intake is seated, your problem should be solved. I say this because you didn't have this problem before you pulled crap apart again. That tells me that something went wrong during re-assembly. Either 1. You adjusted the timing too much or 2. You have that vacuum leak Brian mentioned.
As stated above, you have a vacuum leak. Before you bolt everything down, do the following: 1. obviously make sure all your little vacuum lines are connected (rear of intake, and the 2 "canister" looking thingys at the runners--I think there are 2). 2. Seat the intake and "rock" it back and forth to make sure it's "seated" dead-nuts on. 3. If it's flush, bolt it down.
I am an amateur at this, and I've had my share of removing and reinstalling crap more than once. If your timing is set correctly and your intake is seated, your problem should be solved. I say this because you didn't have this problem before you pulled crap apart again. That tells me that something went wrong during re-assembly. Either 1. You adjusted the timing too much or 2. You have that vacuum leak Brian mentioned.
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