The Impala has push rod engines with variable valve timing. Can't imagine how that works, but I suspect GM has found a cheaper way to use this technology. I am always amazed at how fast new engine technology is used by the Japanese makers and US companies keep putting out old engines. Doesn't this mean they should be able to produce cars for much less than the Asian competition?
New Impala engines
- Thread starter John K
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A few years ago I was told VVT has to have OHC. Go figure, things change.
PS I saw a fleet of new Impala rentals at my company's training center Friday. Looks good, the front is very Accord-ish.
I'm amazed at how the Japanese can meld old and new technologies, like slapping a distributor cap on a 2001 model year DOHC engine.
Except..wait..DOHC engines aren't much newer than distributor caps, are they?
VVT can be fitted to any engine with a camshaft. It simply varies the difference between the crankshaft and camshaft. If you have separate camshafts for intake and exhaust this works even better, but much of the benefit can be realized on SOHC and OHV engines.
brianl703 brings up a good point, japanese engines are no more "high-tech" then american ones. GM started using computer controlled timing in the 70s and by 84 had a full SFI engine, with distributorless ignition, MAF sensor and full computer control. By the late 80s it was practically on every GM car engine. Honda and Toyota took years to integrate this.
Camshaft placement does not equal technological level, just like cylinder count or displacement.
-T
brianl703 brings up a good point, japanese engines are no more "high-tech" then american ones. GM started using computer controlled timing in the 70s and by 84 had a full SFI engine, with distributorless ignition, MAF sensor and full computer control. By the late 80s it was practically on every GM car engine. Honda and Toyota took years to integrate this.
Camshaft placement does not equal technological level, just like cylinder count or displacement.
-T
I'm amazed how fast Impalas depreciate.
http://www.edmunds.com/used/2000/chevrolet/impala/8797/options.html
FWD V8 must be loads of fun in the twisties.
http://www.edmunds.com/used/2000/chevrolet/impala/8797/options.html
FWD V8 must be loads of fun in the twisties.
Have you looked into the "PGM-FI" computer control that Honda was using for fuel injection in 1988? It's PRIMITIVE GARBAGE compared to what's on my 1988 Mustang. 1988 Honda has 13 codes for every single malfunction. It doesn't even have a code for a dead oxygen sensor..that is indicated by "no code" and a "rough idle". Why the **** would a faulty oxygen sensor cause a rough idle? My guess: the ECU isn't sophisticated enough to recognize that the oxygen sensor isn't sending a valid signal and of course continues to use it to control the mixture, leading to a rough idle. That's why it has no code for a faulty oxygen sensor, either.
People fault Ford for not including a data stream output (they eventually started adding it beginning with 1991 models), but my view is that the extensive diagnostic capabilities built right into the ECU made up for it. (As a side note, GM models with an ECU have ALWAYS had a data stream output, even my brother's carbureted 1986 Camaro Z28 had it).
With Honda in the 80s, you got very limited self-test diagnostics and no data stream. I don't believe it even has the capability to store a memory code for an intermittent fault.
Maybe that's why I never see any 80s Hondas on the road around here. I bet they're a real joy to troubleshoot if they fail emissions. EDIT: Bring a lab scope, you'll need it.
[ September 17, 2005, 11:02 PM: Message edited by: brianl703 ]
John K.
Camshafts have been advanced or retarded for years. If you want better low end torque, You advance the cam. If you want more power at the upper end of the rpm scale, you retard the cam timing. Many timing chain(or gear) manufactures have this option. It varies in degrees. My guess is that the cam gear is somehow manipulated by either hydraulic pressure controlled by the ECM or by inertia(Like advance weights in a distributor). This a pure guess on my part but whatever GM did I think it's great. I love it when 50year old designs keep getting better and better.
Camshafts have been advanced or retarded for years. If you want better low end torque, You advance the cam. If you want more power at the upper end of the rpm scale, you retard the cam timing. Many timing chain(or gear) manufactures have this option. It varies in degrees. My guess is that the cam gear is somehow manipulated by either hydraulic pressure controlled by the ECM or by inertia(Like advance weights in a distributor). This a pure guess on my part but whatever GM did I think it's great. I love it when 50year old designs keep getting better and better.
My favorite is the mess of vacuum hoses that required a cover to conceal in the late 80s. My 88 Lesahre has about four vacuum lines. The 3.8s always had a good system, with a MAF sensor and a MAP, for backup. Plus knock control that many makes STILL don't have.
-T
-T
Would the Rhoades lifters in my Pontiac 400 be considered "Variable Valve Timing?"
Wouldn' buy a G.M. .
Interesting ,I totally forgot about thoseI
Rhoades Lifters were great!!! everyone thought you were running solids!! sounded great!
Triple_Se7en
$50 Site Donor 2024
Wouldn't buy Toyotas.
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Yep, I saw the vacuum lines under the hood of a carbureted 80s Accord...at least they were nice enough to number them. Looked like a bowl of vacuum line spaghetti.
Both the 88 Mustang and the 95 and 96 Contour as well as the 91 Escort will run (and drive) with the MAF totally unplugged, there is no MAP on any of them. Makes it easy to do throttle body cleaning with the engine running.
As a side note, when Ford switched from MAP to MAF systems, the MAP became the BAP, barometric air pressure sensor. The MAP and the BAP are almost identical, the only diference being that the BAP doesn't allow you to connect a vacuum line to it, so a MAP can replace a BAP but not vice-versa. With the '91 and newer EEC-IV computers which output 3 digit codes and support datastream output, and with all EEC-IV OBD2 computers, Ford was somehow able to do away with the BAP sensor. They must use an algorithm to generate BAP data from the MAF data, since one of the diagnostic tests for the MAF -- if the vehicle has no BAP sensor -- is to look at the BARO PID and see if it's incorrect, if it is then the MAF is likely bad.
Last September I rode my motorsickle out to Utah from MN for my brothers wedding (that's a whole 'nuther post in itself). Anyways, my parents flew out from Denver and my wife flew in from MN a few days later. My dad let my borrow his rental car, a 2003 Impala, to pick up my wife at the airport, which was about 200 miles round trip. I have never driven one before, and I was quite impressed with it. I'd buy a used one (not a rental though, not the way I hammered that thing down the highway
FWIW, My '87 Legend with PGM-FI does return codes for the O2 sensor...both of them.
Triple_Se7en
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Member # 5626
posted 18 September, 2005 06:33
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quote:
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Originally posted by Steve S:
Wouldn' buy a G.M. .
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Wouldn't buy Toyotas.
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Posts: 921 | From: Michigan | Registered: Dec 2004 | IP: Logged |
I second that.
Member
Member # 5626
posted 18 September, 2005 06:33
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quote:
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Originally posted by Steve S:
Wouldn' buy a G.M. .
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Wouldn't buy Toyotas.
..................... .....................
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Posts: 921 | From: Michigan | Registered: Dec 2004 | IP: Logged |
I second that.
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