I have a 92 Q45 with 85K miles (I have had it since its birth and have had all maintenance performed on the button.)
For the last few weeks I have had occasional days where the car has episodes of "missing" when the car has been cold, lasting up to 10 minutes. It may be right after the car is started or within the first minute or two. The engine light has come on at that time. The problem resolves, as I said, after a few minutes or up to 10+ minutes. I called to make an appt at the dealer but the problem is so intermittant that I can't be certain it will be present when I get there. In adddition, when I called the dealer, there is a new service writer who did not seem to know the first thing about the car, including whether there is any recording of data by a computer when there is an engine problem. I live in Fresno, California and have yet to find an independent Infiniti mechanic, unfortunately.
Is there anything simple that I can check? If this were one of my older cars, I would think plugs or plug wires, coil, a problem with the fuel, and that is about as far as I get....!
ThanksKen K
92 Q45: Intermittent missing when engine is cold
You should get all the fuel injectors tested. I'll bet you have a leaky/failing injector and this is causing the occassional miss? Does it get worse every time it happens? If so, this is probably the problem.
Also, you may have too many carbon deposits in the intake which may be causing a miss. Seafoam should help this problem.
Good luck!
Nick
P.S. How far is Fresno from San Diego? May be worth a drive to Jerry Tucker to get it checked out. He's our "mechanic in the west"
Also, you may have too many carbon deposits in the intake which may be causing a miss. Seafoam should help this problem.
Good luck!
Nick
P.S. How far is Fresno from San Diego? May be worth a drive to Jerry Tucker to get it checked out. He's our "mechanic in the west"
Intermittent missing is usually an electrical problem. It could be a failing injector, or a plug, but I'll guess it's a coil, since those run at high voltage and are far more likely to arc due to bad insulation. I had very similar symptoms back in Feb, except that the missing got progressively worse over time. Eventually the engine began missing constantly. I finally pulled the spark plugs, which proved to be a dead giveaway for which cylinder was bad. I replaced the coil on that cylinder, and I haven't had a problem since.You should pull the plugs. Much harder to do than on a Chevy, but you'll save a lot vs. going to a dealer if you can figure it out on your own. Whatever you do, don't get conned by a dealer that tries to sell you 8 brand new coils just because they're too lazy or greedy to figure out which one is bad.
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Q451990
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- Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
- Location: Columbia, SC
- Contact:
Where are you located? Is the car federal or a CA model?
I assume that since you have had the car since it was new the service manual is still in the trunk (in the plastic tray that covers the spare tire). If you're comfortable with DIY, you can check the codes on the ECU to find out why the check engine light came on. A miss like that can be a bad injector, but unless it's a CA model, I'd be surprised if your check engine light came on for that. Finding out what the code is will help us help you...
I'd say that coil failures are fairly rare but possible (as Nick mentioned. I'd also wiggle the electrical connections on the crank angle sensor and mass air flow sensor. Do this at idle and see if the idle speed changes. Any change in idle indicates a problem - usually connection problems can be fixed by cleaning the contacts and tightening them slightly. I use a dental pick for this, and then put in di-electric grease (available at any auto parts store) to prevent future corrosion.
You might also be able to get the ECU code at AutoZone or some of the other parts places. AutoZone does this free of charge, but sometimes you get what you pay for
Heath
I assume that since you have had the car since it was new the service manual is still in the trunk (in the plastic tray that covers the spare tire). If you're comfortable with DIY, you can check the codes on the ECU to find out why the check engine light came on. A miss like that can be a bad injector, but unless it's a CA model, I'd be surprised if your check engine light came on for that. Finding out what the code is will help us help you...
I'd say that coil failures are fairly rare but possible (as Nick mentioned. I'd also wiggle the electrical connections on the crank angle sensor and mass air flow sensor. Do this at idle and see if the idle speed changes. Any change in idle indicates a problem - usually connection problems can be fixed by cleaning the contacts and tightening them slightly. I use a dental pick for this, and then put in di-electric grease (available at any auto parts store) to prevent future corrosion.
You might also be able to get the ECU code at AutoZone or some of the other parts places. AutoZone does this free of charge, but sometimes you get what you pay for
Heath
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Q451990
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- Location: Columbia, SC
- Contact:
DAEDALUS wrote:I'll bet a pastrami sandwich that the code is knock sensor
So you're betting it's a CA car? No check engine light for the rest of us...
I'm with Doug on this one... had bad knock sensors twice (actually sensors once, and harness the other time) and it never caused a miss. Injectors weren't intermittant in my case either, but I imagine they could be. I'm going with O2 sensors or MAF/CAS connection.
Heath
No, I'm not saying that the knock sensor is causing a miss. I'm saying the miss is caused by something else (I guessed bad coil), and that the roughness is setting off the CEL for the knock sensors. I'm only betting on the CEL code, not the root cause.
Kdkrone, break out that manual, a 10mm driver, a phillips and a flat blade, and settle these high stakes!
Kdkrone, break out that manual, a 10mm driver, a phillips and a flat blade, and settle these high stakes!
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Q45tech
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- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Fuel Ried Vapor Point , missing until the runner section from the injector to the intake valve reaches a 120-150F degrees to avoid the fuel recondensing and puddling.........lean misfire.
The ecu only enrichens the mixture [via higher rpm/amount] just enough to sustain the AVERAGE start up idle speed]........missing actual heats the precats faster. Kind of a time vs emssion volume problem.Throttle body and IAC cleanliness is critical to reducing this phenomenon.
Problem is usually worse in warm starts or warm weather as the start up idle speed doesn't go to 1300 rpm......depending on coolant temp sensor reading.
The ecu only enrichens the mixture [via higher rpm/amount] just enough to sustain the AVERAGE start up idle speed]........missing actual heats the precats faster. Kind of a time vs emssion volume problem.Throttle body and IAC cleanliness is critical to reducing this phenomenon.
Problem is usually worse in warm starts or warm weather as the start up idle speed doesn't go to 1300 rpm......depending on coolant temp sensor reading.
Hi. Sorry I have not been around for the last day to see the responses. Thanks to all.
1. The car is CA.
2. What is the ECU and how do I get information from it?
3. The problem has not happened in the past two days (as I said, it is intermittent). It has happened both with the engine cold and with it hot, usually is resolved within a couple of blocks of driving, but occasionally will last 10-15 minutes.
4. I have pulled out the manual and have begun reading (I am horribly ignorant of the mechanics of this model). For example, I did not realize that each plug has its own coil.
How does an injector "go bad"? Does it clog? Is there any way to clean it, such as an additive?
5. I am all up for a pastrami sandwich and comfortable with both Phillips and flatblade screwdrivers. Just tell me in detail what to do with them...
ThanksKen K
1. The car is CA.
2. What is the ECU and how do I get information from it?
3. The problem has not happened in the past two days (as I said, it is intermittent). It has happened both with the engine cold and with it hot, usually is resolved within a couple of blocks of driving, but occasionally will last 10-15 minutes.
4. I have pulled out the manual and have begun reading (I am horribly ignorant of the mechanics of this model). For example, I did not realize that each plug has its own coil.
How does an injector "go bad"? Does it clog? Is there any way to clean it, such as an additive?
5. I am all up for a pastrami sandwich and comfortable with both Phillips and flatblade screwdrivers. Just tell me in detail what to do with them...
ThanksKen K
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Q451990
- Moderator
- Posts: 11030
- Joined: Tue Jul 23, 2002 8:21 am
- Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
- Location: Columbia, SC
- Contact:
Ken,
Your first step would be to locate the MAF (mass air flow sensor) and CAS (crank angle sensor) and wiggle those connections while the car idles. Any change in idle speed is a sure sign of a weak connection. You can tighten them with a small pick (I use an old dental pick) and then lubricate the connection with dielectric grease (available at auto parts stores) to stop any corrosion and keep moisture out.
Check out the entire EF&EC section of your service manual. In mine the ECU check starts on EF&EC-51.
Heath
Your first step would be to locate the MAF (mass air flow sensor) and CAS (crank angle sensor) and wiggle those connections while the car idles. Any change in idle speed is a sure sign of a weak connection. You can tighten them with a small pick (I use an old dental pick) and then lubricate the connection with dielectric grease (available at auto parts stores) to stop any corrosion and keep moisture out.
Check out the entire EF&EC section of your service manual. In mine the ECU check starts on EF&EC-51.
Heath
I have been traveling more than I have been home, soI have not been around to respond.
Here is the latest: I did two things to the Q last week.
1, I cleaned whatever dirt and oil I could from the plugs, connectors, etc.
2. I put a can of Techron in the gas tank.
Since that time, my problem has not recurred.... go figure...
Ken K
Here is the latest: I did two things to the Q last week.
1, I cleaned whatever dirt and oil I could from the plugs, connectors, etc.
2. I put a can of Techron in the gas tank.
Since that time, my problem has not recurred.... go figure...
Ken K