I have a 95Q just hit 87K.Q45 Tech has me completely neurotic about these. It's like I have bad dreams where my injectors won't stop failing and hoses keep breaking, causing these terrible overheats....Were these two problems fixed by 95? I read a post by Q45 Tech where he states the injectors earlier models have pintel injectors, and that changed in 94 did that help stop the problem?Do you guys think I should change out my plenum hoses?
Thanks,Robert
Plenum Hoses & Fuel Injectors
Not to make you neurotic, but mine went at 88K. However, it was not a catastrophic failure -- a small leak of fuild that you could see in pooling under the plenum and smell. Yet, even if your hoses do not leak, by this age they are brittle from heat and age. Thus, you should probably plan to have them done soon. The mechanic that I worked with showed me how even the non-leaking hoses have the flexibility of concrete! Just cracked off the fittings. In a 90-96Q, seems like this is an every 90-100K service item.
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natsoundup
- Posts: 669
- Joined: Fri Jul 26, 2002 4:27 am
No special tools I remember. It's just the most tedious job I've experienced on the car. The first 45 minutes went great!natsoundup wrote:How difficult is it to take off the plenum and replace all the hoses....
I am more concerned about special tools needed to get the job done...
Driver's side O2 sensor wire is tie-wrapped to a bracket on the back of the plenum. Make sure you free this before trying to pull the plenum off the motor. Leaky coolant hoses ("coolant bypass kit" from Scottsdale) are not included with Scottsdale's under-plenum hose kit. At least they weren't 6 months ago.
Stunning how light and easily sliced these coolant-bypass hoses are. Some of the larger under-plenum vacuum hoses are internally armored, which may help explain the "rock like" hardness of some of the new ones.
Sorry, I forget who (Dadaelus?), but someone suggested a hose-removal tool something like an ice-pick with a hook at the end. That might have saved time and $$, but it was too late by the time I read the suggestion -- I had already cut the hoses to get the plenum off. It's a bear trying to save good hoses. You start cutting eventually.
Inspect knock sensors for cracks while you're in there!
landtodd wrote:Inspect knock sensors for cracks while you're in there!
This touches on an important point, that ideally you should have another car available in case the job takes more than a weekend OR that you should do as much research as you can to ensure that you have ALL the parts necessary before starting the job. I prefer the first method, but not everyone has cheap access to a second vehicle. Kind of a take-a-chance thing otherwise, like hoping the knock sensors aren't cracked, or hoping that you got all hoses and gaskets required.As far as the pick, I did mention it, but the credit goes to DougQ45, who showed me how handy they really are.I'll agree that there are no "special" tools required, but don't be surprised if your tool set needs some "enhancing" either. Gearwrenches are fabulous and, to me, just short of air tools in how much easier they make my life. When I did the covers/plenum, I did have to run to Sears a few times for a few extra tools.
That steamy puddle of dirty water in the motor's valley can lead to corrosion in the knock-sensor wiring harness. It doesn't take a whole lot of corrosion before the ECU can't "see" one or the other of its knock sensors. The ECU then goes into "limp home" mode, which is about the most obnoxious thing it could do. I think it's a good idea to replace the knock-sensor wiring harness (~$55 Scottsdale) if it's been under water. Good to fix the leak quickly at any rate.
Oh, and save the 8 metal rings that join the 8 legs of the plenum to the 8 intake runners. The Scottsdale kit contained only the soft plastic gasket.
Yup, Daedalus is right. Count on not using the car for a while.
Because there's a $5 cover charge at my local Infiniti dealer (kidding, but just barely), I got my parts from Scottsdale, as usual. Given the upredictability of what you'll find under the plenum, I'm not sure it's possible to get everything you'll need in the first order. You're going to run into (or out of) something.
Anyway, for this job, I ordered from Scottsdale 3 times, with a week's wait for shipping each time. And then, dopey me, I ordered O2 sensors *after* the plenum was off. Sparkplugs.com has great prices on NGK O2 sensors, but what I didn't know is that 3 weeks seems to be their normal shipping time. (The plenum doesn't have to be off to replace the sensors, but I rolled the jobs together since it's a little easier with plenum off.)
This is one job where having a well stocked, reasonalby priced parts department close at hand would be an advantage. The downside of doing it yourself is that the car is almost certainly laid up longer than it would have been if you had the job done. The upside is the savings, of course:
8 hours book labor (* $75/hr) = $600 O2 sensors from Sparkplug = $200 rest of the parts from Scottsdale = $100
That's almost a grand saved. I could have done it faster had I bought the incidental parts locally. Good, cheap, or fast. Pick just two.
There's a hidden cost of DIY that we rarely consider. Most cars are depreciating assets, and most DIY'ers take longer than professionals. How much *additional* depreciation did the car suffer during the *additional* time it was off the road, compared to having the job done professionally and having it back the next day? Include depreciation and other fixed expenses like taxes, tags, and insurance, none of which you got any use of while the car was laid up.
Depreciation, insurance, and tags, my '92 Q costs me about $5 a day. It was off the road for almost two months (that won't happen again), so in two months, I spent $300 on it and got nothing in return. I saved $300 less on the job, compared to having it done. There are other intangibles to consider -- the education was immensely valuable to me, satisfaction, peace of mind, and knowing the job was done right. I'm still glad I did it, and I'm still ahead of the game.
Oh, and save the 8 metal rings that join the 8 legs of the plenum to the 8 intake runners. The Scottsdale kit contained only the soft plastic gasket.
Yup, Daedalus is right. Count on not using the car for a while.
Because there's a $5 cover charge at my local Infiniti dealer (kidding, but just barely), I got my parts from Scottsdale, as usual. Given the upredictability of what you'll find under the plenum, I'm not sure it's possible to get everything you'll need in the first order. You're going to run into (or out of) something.
Anyway, for this job, I ordered from Scottsdale 3 times, with a week's wait for shipping each time. And then, dopey me, I ordered O2 sensors *after* the plenum was off. Sparkplugs.com has great prices on NGK O2 sensors, but what I didn't know is that 3 weeks seems to be their normal shipping time. (The plenum doesn't have to be off to replace the sensors, but I rolled the jobs together since it's a little easier with plenum off.)
This is one job where having a well stocked, reasonalby priced parts department close at hand would be an advantage. The downside of doing it yourself is that the car is almost certainly laid up longer than it would have been if you had the job done. The upside is the savings, of course:
8 hours book labor (* $75/hr) = $600 O2 sensors from Sparkplug = $200 rest of the parts from Scottsdale = $100
That's almost a grand saved. I could have done it faster had I bought the incidental parts locally. Good, cheap, or fast. Pick just two.
There's a hidden cost of DIY that we rarely consider. Most cars are depreciating assets, and most DIY'ers take longer than professionals. How much *additional* depreciation did the car suffer during the *additional* time it was off the road, compared to having the job done professionally and having it back the next day? Include depreciation and other fixed expenses like taxes, tags, and insurance, none of which you got any use of while the car was laid up.
Depreciation, insurance, and tags, my '92 Q costs me about $5 a day. It was off the road for almost two months (that won't happen again), so in two months, I spent $300 on it and got nothing in return. I saved $300 less on the job, compared to having it done. There are other intangibles to consider -- the education was immensely valuable to me, satisfaction, peace of mind, and knowing the job was done right. I'm still glad I did it, and I'm still ahead of the game.
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Q451990
- Moderator
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- 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
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Interesting theory on the depreciation and associated costs... why oh why has Q2 been in my garage for over a year now!! 
The good news is that a lot of these are fixed costs, at least in the short term, so unless you're getting rid of the car vs. keeping it they don't really apply. That's at least how I justify it...
Heath
The good news is that a lot of these are fixed costs, at least in the short term, so unless you're getting rid of the car vs. keeping it they don't really apply. That's at least how I justify it...
Heath
Todd, great analysis. I like your "total-picture" thinking. Sorry to spoil your bookkeeping, but I think you only saved $100 on the O2 sensors. The factory ones are $103.70 each, last time I ordered, and I think the ones you got were about $50 each. But on the flipside I think you might be underestimating your savings on the other parts you bought from Scottsdale.
It's also hard to calculate depreciation. Our cars don't have a straight -line depreciation. If you buy a used Q for , say, $5,000., and maintain it in the way NICO members do, it will stay worth $5,000. for some time. But, if it breaks, it is worth nothing. So, you don't lose anything by having the car out of service, except use of it.
Daedalus -- you don't miss a thing! Price comparison on the O2 sensors was with local dealer, who would charge $145 ea if only I were desperate enough to pay it. The local price changes according to how the Seminoles did last weekend, the phase of the moon . . . I think my dealer is in the business of making a new Infiniti appear more attractive by ratchetting up parts prices for old ones.
Fxjackso -- Dennis came up with a handy rule-of-thumb for estimating depreciation. I called it the three-year half-life. The average car loses half its value every three years. With some adjustment, that works pretty well.
Even gen-1 Q45s are still commodities, depreciating, their value governed by the larger commercial market. Sadly, you don't get anything in a commercial trade for solid maintenance or complete records, yet commercial transactions determine our cars' ballpark values. If the car goes forward and reverse, and doesn't emit too many suspicious noises or odors, appearance is what counts in a trade, not because car dealers are evil or stupid, but because appearance is what used-car buyers buy. (Generalizing, of course.)
I understand your point -- your well maintained car will be worth more to a knowledgable Q45 buyer, maybe 20% more than market, but the general price range is set by the commercial market and its 3-year half-life.
Three years from now, I expect my Q to be worth something like $2000 in a private-party sale (worthless in wholesale or trade-in), but if you're smart or lucky, you go off the beaten path and find educated buyers. Like NICO members! I expect a NICO member might pay $2400 for it, knowing what's been done and what's important.
After 10 years, the car is worth so little that we're starting to talk about nickels and dimes of depreciation, and it becomes academic. You're right -- hard to estimate. At 13 years old, the three-year rule says we're talking something like 6% of original value, so I admit to splitting hairs. My zero-miles cost of $5/day is an estimate, half of which is depreciation, but it rolls up into $150 a month, which might be something to consider when you're watching your nickels and dimes.
I'm convinced that depreciation is a real cost by two extreme cases, one hypothetical, one real.
Let's say the chain-guide problem was known in 1992. Let's say I buy my Q new for $40K in 1992, and decide to replace the guides myself that year. Because I'm forgetful, a novice, and so incredibly slow, the car sits half-completed for 10 years before I'm done! Sure I saved a thousand (or more) doing the job myself, but in the interim, the car has depreciated $35K.
If it could have been done professionally in two days for between $1500 (T3) and $4500 (my dealer -- Seminoles lost), then I would have gotten 10 years of use out of the car, and ended up in almost the same place, value-wise.
We all lose money on depreciating assets (cars) over 10 years, whether we drive them or not, but generally we put up with that because we get transportation in return. Spending money and getting nothing in return is just throwing money away, which we do any time the car is laid up.
I think accountants call it "opportunity cost."
True story -- a friend of mine decided in 1992 that he wanted a 10-year-old Mustang with low miles in 2002. He thought ahead and actually bought a new Mustang, put it in a garage, and waited 10 years. (I think he put 5000 miles on it.) What he got was a 10-year-old car for the price of a new one!
They're the same stories -- the car depreciates whether you use it or not. The only difference is in the reasons for taking the car off the road for an extended period of time.
Fxjackso -- Dennis came up with a handy rule-of-thumb for estimating depreciation. I called it the three-year half-life. The average car loses half its value every three years. With some adjustment, that works pretty well.
Even gen-1 Q45s are still commodities, depreciating, their value governed by the larger commercial market. Sadly, you don't get anything in a commercial trade for solid maintenance or complete records, yet commercial transactions determine our cars' ballpark values. If the car goes forward and reverse, and doesn't emit too many suspicious noises or odors, appearance is what counts in a trade, not because car dealers are evil or stupid, but because appearance is what used-car buyers buy. (Generalizing, of course.)
I understand your point -- your well maintained car will be worth more to a knowledgable Q45 buyer, maybe 20% more than market, but the general price range is set by the commercial market and its 3-year half-life.
Three years from now, I expect my Q to be worth something like $2000 in a private-party sale (worthless in wholesale or trade-in), but if you're smart or lucky, you go off the beaten path and find educated buyers. Like NICO members! I expect a NICO member might pay $2400 for it, knowing what's been done and what's important.
After 10 years, the car is worth so little that we're starting to talk about nickels and dimes of depreciation, and it becomes academic. You're right -- hard to estimate. At 13 years old, the three-year rule says we're talking something like 6% of original value, so I admit to splitting hairs. My zero-miles cost of $5/day is an estimate, half of which is depreciation, but it rolls up into $150 a month, which might be something to consider when you're watching your nickels and dimes.
I'm convinced that depreciation is a real cost by two extreme cases, one hypothetical, one real.
Let's say the chain-guide problem was known in 1992. Let's say I buy my Q new for $40K in 1992, and decide to replace the guides myself that year. Because I'm forgetful, a novice, and so incredibly slow, the car sits half-completed for 10 years before I'm done! Sure I saved a thousand (or more) doing the job myself, but in the interim, the car has depreciated $35K.
If it could have been done professionally in two days for between $1500 (T3) and $4500 (my dealer -- Seminoles lost), then I would have gotten 10 years of use out of the car, and ended up in almost the same place, value-wise.
We all lose money on depreciating assets (cars) over 10 years, whether we drive them or not, but generally we put up with that because we get transportation in return. Spending money and getting nothing in return is just throwing money away, which we do any time the car is laid up.
I think accountants call it "opportunity cost."
True story -- a friend of mine decided in 1992 that he wanted a 10-year-old Mustang with low miles in 2002. He thought ahead and actually bought a new Mustang, put it in a garage, and waited 10 years. (I think he put 5000 miles on it.) What he got was a 10-year-old car for the price of a new one!
They're the same stories -- the car depreciates whether you use it or not. The only difference is in the reasons for taking the car off the road for an extended period of time.
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greg_atlanta
- Posts: 1111
- Joined: Tue Jul 23, 2002 4:37 pm
- Car: 2008 G35 Journey Sedan, silver/black (no sunroof), 1992 Q45 (in a past life)
I've learned it's foolish to even think about selling a 10 year old car that's paid for. The only way to get a good value out of it is to USE IT!
I always worry over repair costs, but have to remember that a new car payment of $500 per month is $6000 per year -- and a used car payment of $300 per month with $100-200 per month maintenance & repairs isn't much different!!!
I'm still freaked about getting in an accident -- anything other than a scratch will total the car -- but I'm saving money with no collision or comprehensive coverage and that'll make it a lot easier to say BYE-BYE! when the time comes.
I always worry over repair costs, but have to remember that a new car payment of $500 per month is $6000 per year -- and a used car payment of $300 per month with $100-200 per month maintenance & repairs isn't much different!!!
I'm still freaked about getting in an accident -- anything other than a scratch will total the car -- but I'm saving money with no collision or comprehensive coverage and that'll make it a lot easier to say BYE-BYE! when the time comes.
Hey Greg. I *completely* agree about keeping a paid-for Q45. To me, that's close to the best of all possible worlds. The only thing that might come close is an early 80s 911. Or something completely impractical like a 60s Cadillac convertible.
From a recent copy of Road&Track, I priced the new Neon turbo over 5 years, and I can't believe what the payments were! Since my labor is "free," I don't spend anywhere near that much on the Q. Two whole years of Q45, and all I've spent is the equivalent of 3 Neon payments. If the dealership had done the past two years of my work (mostly preventive maintenance which will keep costs down later), I would have spent almost *exactly* two years of Neon payments. However, at the end of those two years, I would still own a whole Q45 (worth ~$4000) instead of half a Neon (also worth ~$4000).
Huh, that worked out pretty neatly.
Let's see. If the transmission went out tomorrow, that would be another 6 Neon payments, and I'm still ahead -- 9 Neon payments for 24 months of Q45. I hope you end up getting your A/C fixed -- just 6 Neon payments!
For maintenance and repair, the Q needs "good," and I need "cheap." "Fast" takes a sideline. It means DIY for me, even if the car is laid up longer than it has to be. Whether we count downtime or not, DIY has saved me 15 Neon payments.
At the risk of repeating myself for the umteenth time, I don't trust anyone in Tallahassee to work on the Q. You probably remember it was the dealer's replacement of the knock sensors (previous owner) that caused the coolant leaks that made me remove the plenum last summer. Go back to the dealer? No thanks!
Like you, I'm nervous about accidents for the same reason -- fender-bender = totaled. But just like you describe, that's a significant hidden beauty of owning a car that's not worth much. Walk away from it instead of being forced to patch up a never-be-right-again carcass.
I'm not saving as much on insurance as you probably do. Liability is required in Florida, so that's the expensive insurance. Collision and Comprehensive add only about $200 a year to my premiums. Even at that, it's getting expensive for the amount of coverage (as the car declines in value). I'll probably drop C&C next year.
Financing a car isn't a trap you'll ever see me walking into. If push comes to shove and times get really bad, you can delay maintenance, but you can't delay car payments.
From a recent copy of Road&Track, I priced the new Neon turbo over 5 years, and I can't believe what the payments were! Since my labor is "free," I don't spend anywhere near that much on the Q. Two whole years of Q45, and all I've spent is the equivalent of 3 Neon payments. If the dealership had done the past two years of my work (mostly preventive maintenance which will keep costs down later), I would have spent almost *exactly* two years of Neon payments. However, at the end of those two years, I would still own a whole Q45 (worth ~$4000) instead of half a Neon (also worth ~$4000).
Huh, that worked out pretty neatly.
Let's see. If the transmission went out tomorrow, that would be another 6 Neon payments, and I'm still ahead -- 9 Neon payments for 24 months of Q45. I hope you end up getting your A/C fixed -- just 6 Neon payments!
For maintenance and repair, the Q needs "good," and I need "cheap." "Fast" takes a sideline. It means DIY for me, even if the car is laid up longer than it has to be. Whether we count downtime or not, DIY has saved me 15 Neon payments.
At the risk of repeating myself for the umteenth time, I don't trust anyone in Tallahassee to work on the Q. You probably remember it was the dealer's replacement of the knock sensors (previous owner) that caused the coolant leaks that made me remove the plenum last summer. Go back to the dealer? No thanks!
Like you, I'm nervous about accidents for the same reason -- fender-bender = totaled. But just like you describe, that's a significant hidden beauty of owning a car that's not worth much. Walk away from it instead of being forced to patch up a never-be-right-again carcass.
I'm not saving as much on insurance as you probably do. Liability is required in Florida, so that's the expensive insurance. Collision and Comprehensive add only about $200 a year to my premiums. Even at that, it's getting expensive for the amount of coverage (as the car declines in value). I'll probably drop C&C next year.
Financing a car isn't a trap you'll ever see me walking into. If push comes to shove and times get really bad, you can delay maintenance, but you can't delay car payments.
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greg_atlanta
- Posts: 1111
- Joined: Tue Jul 23, 2002 4:37 pm
- Car: 2008 G35 Journey Sedan, silver/black (no sunroof), 1992 Q45 (in a past life)
landtodd wrote:Financing a car isn't a trap you'll ever see me walking into. If push comes to shove and times get really bad, you can delay maintenance, but you can't delay car payments.
I'll probably fall into that trap... as long as I can get 2 more years out of the Q (maybe 3), stash some cash, and say bye-bye to credit cards, I can afford $400-500/mo payment on something I like enough to keep forever!! (with extended warranty, of course)
Not being able to keep up with repairs because of finances gets annoying. And never reaching perfection gets annoying too (like trying to fix vibrations & rattles).
But owning an old car is a great education on how to make a new car last forever!!
:rolleyes
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natsoundup
- Posts: 669
- Joined: Fri Jul 26, 2002 4:27 am
greg--- it's funny how you say that...
nearly 5 years ago, I bought our first new car (truck) . A Ford Expedition..... my wife drives it.... that's how I got the 90Q...years ago I used to work on cars and really thought I got to understand them....then too much technology got in the way...
Anyway.... the truck has 80k miles....nothing has gone wrong...but I change the fluids regularly and try to take care of it as well as all of my used cars. I expect 175k out of it with little to go wrong...much of which I expect to do on my own. I even got the extended warranty....and I haven't even been able to use it.
I attribute that to years of owning used cars.... before the Q I had a 72 Mercedes for 12 years.... probably the best car I ever owned....paid 5500 ....sold for 4800.... probably averaged 1200 a year in repairs and maintenance (actually little went wrong).... you do the math on ownership on that one..... I could never duplicate ownership costs....
For now, I'll live with the Q, but I won't get emotional over it... one big repair.... and I'll part it out..
To this day I am looking for another 72 280 SE.... oh well... I have to suffer with the Q
nearly 5 years ago, I bought our first new car (truck) . A Ford Expedition..... my wife drives it.... that's how I got the 90Q...years ago I used to work on cars and really thought I got to understand them....then too much technology got in the way...
Anyway.... the truck has 80k miles....nothing has gone wrong...but I change the fluids regularly and try to take care of it as well as all of my used cars. I expect 175k out of it with little to go wrong...much of which I expect to do on my own. I even got the extended warranty....and I haven't even been able to use it.
I attribute that to years of owning used cars.... before the Q I had a 72 Mercedes for 12 years.... probably the best car I ever owned....paid 5500 ....sold for 4800.... probably averaged 1200 a year in repairs and maintenance (actually little went wrong).... you do the math on ownership on that one..... I could never duplicate ownership costs....
For now, I'll live with the Q, but I won't get emotional over it... one big repair.... and I'll part it out..
To this day I am looking for another 72 280 SE.... oh well... I have to suffer with the Q