| Author | Message | ||
     Gordon Norris Prolific User Username: crewes_missile Post Number: 111 Registered: 2-2005 |
Came across this listing by accident while researching thermostats. The throttle position potentiometer/sensor(TPS) for fuel injected Spirits/Spurs etc RR Part No UE 45749 is an AC Delco Part No:213-2737 also fitted to numerous Alfa's, Fiats and Lancia's. The AC Delco listing says it is suitable for all fuel-injected Spirits/Spurs and Turbo's up to, BUT NOT INCLUDING the 4 speed auto introduction in MY1992. Should be cheaper than buying from Crewe. GN. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 669 Registered: 4-2003 |
Great. I have been dreading buying one from an independent, not even Crewe, one day at £600 / A$1500 + GST, Exchange at that ! Curious is that it is not a Bosch part like the rest of the electronic system. Any ideas ? | ||
| Gordon Norris Prolific User Username: crewes_missile Post Number: 112 Registered: 2-2005 |
Richard, I was thinking the same thing, and was going to ask if anyone knew why it was not a Bosch part. Then I checked a Bosch listing I have of all the engine management components fitted to all these cars, and sure enough, the "throttle position sensor" is NOT listed, BUT a "throttle valve sensor" IS which after considering I'm assuming is the TPS and is BOSCH Part No: 0 280 120 300, so it looks as though the AC Delco may be a substitute..it is identical to the OEM by the look of it. I tried to download the photo, but the AC Delco site converted it to gibberish, probably for copyright. Interestingly, AC Delco do not list the post-92 part for the 4 speed auto, but Bosch do have a listing for a throttle valve sensor and it is a different number(to accomodate an extra switch for the 4 speed gearbox ECU). It is good to know there is an alternative, as the TPS is one of the harder working pieces with regard to mechanical wear, but we need to compare the AC Delco price to the Bosch price just the same, either via Bosch or via Alfa/Fiat/Lancia. I have little doubt the AC Delco would be cheaper, but it may have to be shipped from the US. And any part, Bosch or AC Delco should be cheaper via Alfa/Fiat/Lancia than via Crewe. Interestingly the AC Delco part doesn't fit any homegrown US cars, so why they should make a substitute part for such a small niche market of Bentleys, RR's and "Alfiatcia's" is strange. GN. | ||
| Larry Halpert Prolific User Username: larry_halpert Post Number: 57 Registered: 9-2003 |
It seems that some Sobs use it, too. Advertised for about $48 US. From the list, it appears to be for K-Jetronic cars as well (like my '89 Spur.) Here's the AC Delco & Bosch pics:   Larry | ||
| Gordon Norris Prolific User Username: crewes_missile Post Number: 114 Registered: 2-2005 |
Thanks for the pics Larry. The AC Delco site didn't let me pinch the pic. Like I said they are damn near identical to look at. The US$48 for the AC Delco part is a huge difference!!! A completely accidental find while I was looking for the thermostat...(no luck on that front yet by the way) Pardon my ignorance Larry, but what's a "Sob"...and don't tell me it's "son-ofa-b...."  GN. | ||
| Larry Halpert Prolific User Username: larry_halpert Post Number: 58 Registered: 9-2003 |
Oh sorry, I mean Saab. Larry | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 674 Registered: 4-2003 |
Larry and Gordon, That's amazing work. The silly price I mentioned must be for the complete assembly, fuel distributor and all. Given that the air flow potientiometer is the heart of the system and the most likely to fail as Gordon points out, you guys have probably saved us heaps in the future. Great news that Saab uses them too. Next time I pass the Bosch agent I'll get a quote as a reference. RT. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 675 Registered: 4-2003 |
Larry: thanks again. Here they are at $48 for a Saab, called a throttle switch. By chance, I had a look at it while doing the fluid checks: there's quite a bit of fruit salad to remove before you can access the little devil ! http://www.maximumautoparts.com/SA_Throttle~Switch_mo.html | ||
| Gordon Norris Prolific User Username: crewes_missile Post Number: 115 Registered: 2-2005 |
At least the Saab connection makes some sense re the AC Delco part, both companies being GM. But at only $48 for original Bosch, who cares? Now I wonder what the Crewe price is.... (....usually: think of a reasonable price and multiply by 10!)  GN. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 678 Registered: 4-2003 |
Gordon, The name Throttle Position Switch had me curious as I have fortunately never dealt with this device and assumed it to be a potentiometer. I assumed it was an air flow meter as on the more troublesome fuel-rail systems with which I have some experience. Indeed, it is a switch and not a potentiometer. It is simply a two-way single-pole switch, basically a pair of microswitches. One is closed on idle and the other on high throttle. On naturally aspirated cars without an electronic closed-loop Lambda CO controller (basically a purely mechanical K-Jetronic injection system), the switch is only for the transmission kickdown and has nothing to do with the fuel injection. Maybe the GM 3L80 transmission connection is why it is a listed Delco unit after all. With Lambda control on K-Jetronic cars, ie with electronic CO regulation, it also shuts the closed-loop control down on high-throttle openings but not much else. On KE Jetronic cars (early injected Turbos) and K-Motronic like yours, the TPS affects the ignition and Lambda control as well. This will probably explain a bit about the different unit on 1992+ 4-speed cars. I'l bet it controls the torque converter lockup on those cars ! I'll bet you a packet of crisps that you can easily open them up and replace the microswitches. RT. | ||
| Larry Halpert Prolific User Username: larry_halpert Post Number: 59 Registered: 9-2003 |
Which naturally aspirated cars with K-Jetronic would have the electronic CO control? What would symptoms be that this switch is not working? Larry PS: another purely emmissions item by AC Delco is the Air Pump Check Valve #214-403. About $15 US copmpared to about $80 US Rolls price. | ||
| Gordon Norris Prolific User Username: crewes_missile Post Number: 119 Registered: 2-2005 |
Richard, I think I'll take that pack of crisps, as I'm 90% sure I've seen a pic of the insides of one of these and I think they are a simple wiper and contact arrangement. Nothing even as fancy as microswitches. (I won't bet more than a pack of crisps on it though!) Just can't recall where I saw it. RR/B confuse the issue by referring to it in the manual as a "Throttle position sensor", but then if you search in the parts catalogue you won't find it..it's listed as a "throttle potentiometer", which of course it isn't as you point out; The Bosch description of "throttle position switch" is, in fact, the most accurate. The post '92 ones do have a potentiometer, but your car and mine have a simple switch arrangement. For K-Jetronic it identifies idle, part load, and full load. (part load occurs when the switch contacts are broken between idle and full load)It performs the simple functions you describe. For K-Motronic, a timer comes into play in the Motronic to detect not only the switch positions but the speed of transition from one mode to the other, so with some fuzzy-logic it identifies idle, overrun, partload, and full load. The Motronic uses this to compute correction factors for ignition, fuel, turbo boost where applicable, kickdown, etc (and if fitted with a transient boost kit, the speed of throttle application, once again to activate the transient boost.) On post-'92 cars with the 4 speed auto, the manual says: "The throttle position sensor (TPS) is mechanically connected to the throttle shaft. It is basically a potentiometer with one end connected to a 5 volts feed from the TCM (transmission control module) and the other to earth. A third wire is used by the TCM to measure voltage across the TPS potentiometer. As the throttle is depressed, voltage increases from approx. 0.25 to a max of 4.2 volts (cars prior to 1994 model year) or 0.6 to a max of 3.8 volts (1994 MY onwards). Therefore, the TCM monitors voltage from the TPS and adjusts the transmission shift pattern based on engine load. In a sense, the TPS has replaced the vacuum modulator used on 3-speed transmissions.)" Larry, in answer to your Q's: 1/which cars: if the car has an oxygen sensor and cat. 2/Symptoms of not working on such a car: if full load contact fails-no kickdown (this can also be due to maladjustment of linkage and/or TPS); if idle contact fails, no closed loop control on idle mixture ie/ richer at idle/greater emissions. And Larry, you're a marvel at finding obscure substitutes. Luckily I don't have to worry about emmision gear on my car, but that Air Pump check valve info will definitely be useful to many. Richard, at least the TPS being a simple device, if, in 50 years no replacement was available, one could very easily be home-made with a cam or lever and a couple of microswitches. ...now I feel like chips...now where the hell did I see that internal picture.... GN. |
