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Discussion Starter #1
Anyone know where i can get a replacement cat for the v8 turbo Esprit? the aftermarket units create too much backpressure. The dealer says its on back order for 3 weeks. Would be interested in a Used or new unit :(
 

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From everything I have read, it's the other way around. The stock cats are much higher back pressure than the aftermarket systems.

Correct me if I am wrong.


1998 Lotus Esprit V8
 

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Discussion Starter #3
your probably right. the left side cat is still original and the passenger side is the one i've replaced. i was thinking maybe changing the left side to an aftermarket unit also would fix the issue. The mechanic who was working on it said that might not work but i think its the difference in back pressure that is causing the problem.

anyone here have any experience with aftermarket cats?
 

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just responded to you PM and I touched aftermarket cats. If you have any other questions let me know, I did tons of research before buying.
 

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200 cell metal substrate Cats create less back pressure than the OEM, but in California we are required to run OEM only. Most smog shops would not know what a OEM Cat looks like, but you never know! I would never think of putting a 200 cell aftermarket Cat in an OEM case!
 

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a local guy here has needed to replace his original V8 cats several times (covered by Lotus on his '03). But it seems those original ceramic cats just don't hold up... I would go to metal aftermarket cats... IMO
That sounds more like he had an issue with engine tune that was destroying his cats. I can imagine a dealer that was happy to replace the cats while Lotus was paying under warranty without bothering to figure out if there was another root cause.
 

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It was a stock '03 V8. don't think it was driven hard, and seeing how the OP also had to replace a cat...
We'll never know for sure, but even if it's stock and driven gently, if any faulty condition caused the engine to run rich, it would burn up the cats.
 

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Why don't you just replace with a piece of exhaust tubing and not waste $$ on it? The only thing I own that has a cat is my woodstove of all things rotfl
 

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Discussion Starter #14
update! i changed the left cat with another universal and now it seems to run better.

however I just got a P0108 MAP sensor code. anyone else have any issues with map sensors?
 

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P0108 Manifold Absolute Pressure/Barometric Pressure Circuit High Input

Potential causes of a P0108 code:

Bad MAP sensor
Leak in vacuum supply line to MAP sensor
Engine vacuum leak
Short on signal wire to PCM
Short on reference voltage wire from PCM
Open in ground circuit to MAP
Worn engine causing low vacuum


Possible Solutions

A good way to diagnose if the MAP sensor is to blame would be to compare the KOEO (key on engine off) MAP sensor reading on a scan tool with the Barometric pressure reading. They should be the same because they both measure atmospheric pressure.

If the MAP reading is greater than 0.5 volt off of the BARO reading, then replacing the MAP sensor would likely fix the problem. Otherwise, start the engine and observe the MAP reading at idle. It should normally be about 1.5 volts (varies according to altitude).

a. If it is, the problem is likely intermittent. Check all the vacuum hoses for damage and replace as necessary. You can also try wiggle testing the harness and connector to reproduce the problem.
b. If the scan tool MAP reading is more than 4.5 volts, check the actual engine vacuum reading with the engine running. If it is less than 15 or 16 in. Hg, then the PCM is probably not seeing enough vacuum (due to a worn engine, perhaps) for a given operating condition (which causes a higher than normal voltage signal to the PCM) and setting the code. Repair the engine vacuum problem and retest.
c. But, if the actual engine vacuum reading is 16 in. Hg or more, then unplug the MAP sensor. The scan tool MAP reading should indicate that there is no voltage present. Check that the ground from the PCM is intact and also that the MAP sensor connector and terminals are tight. If the connection is good, then replace the map sensor.
d. However if, with KOEO, & the MAP sensor unplugged, the scan tool shows a voltage reading, then there may be a short in the harness to the MAP sensor. Turn the ignition off. At the PCM unplug connector and remove the MAP signal wire from the connector. Re-attach the PCM connector and see if with KOEO, the scan tool MAP reading shows voltage. If it still does, replace the PCM. If not, check for voltage on the signal wire you just removed from the PCM. If there is voltage on the signal wire, find the short in the harness and repair.
 
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