Low performance during acceleration - SOLVED

[RobertK]

I have a new problem with my Japan import 1992 500E:

The performance during acceleration between 3000-5000 rpm is very low, it looks like the car is standing still and stays on the same speed. The engine revs during this.

It also not revs to 6000 RPM. I doubt if this is limb-mode because of the fact that below during low speed the performance is normal.
No lights are on during this (ASR+ABS).

Could a defect acceleration switch the one near the pedal be the cause of this ?

Moderator edit: See post #32 for the solution.

 

[gsxr]

You need to check fault codes on all modules to start with.

I don't understand what you mean when you say "looks like the car is standing still and stays on the same speed. The engine revs during this."

Have you checked for plugged catalysts / exhaust backpressure?

 

[RobertK]

To pinpoint my other problem with the ASR/ABS lights the modules are all checked on fault codes last friday by Classic Center.
Only (old) ones for the right wheel ABS sensors front and behind wheel came up (and not along with the ABS/ASR block vent like before).

I mean: the car does minimal accelerate (in the 3000-5500 area) until it revs on maximum aprox. 5000-5500 with a lot of effort and this takes a long time, no power, it feels as a sort of power-surge at the end with minimal hitch.

My other issue with the raising temp. could also have probably a correlation with this.
Probably one of my fuel-pumps is defect ?

No, how do I test that exhaust backpressure ?

 

[gsxr]

No, how do I test that exhaust backpressure ?

Free test: Remove the exhaust crossover pipe, go for a very loud test drive. If all problems are gone, the cats are plugged.

Sciency test: Use an exhaust backpressure gauge connected ahead of the catalysts, either screwed in place of the O2 sensor, or drill a small hole to allow the gauge fitting to attach. You must be able to view the gauge while driving. When driving under load, if pressure exceeds 2-3psi (even at WOT near redline), the exhaust is restricted. If really bad, you'll be able to make the gauge spike to 10-15psi whenever you press on the pedal. Doesn't work in the driveway in park or neutral, you need to drive the car. Normal is below 3psi at WOT anywhere between idle and redline.

Quieter / quick test: Read this post and test drive with a vacuum gauge attached. NOTE: this test may not be conclusive! The other 2 tests above are foolproof. Especially the first/free/noisy test.

 

[maw1124]

+1 betting plugged cats.

maw

 

[B16 NYK]

+2 on blocked cats

 

[RobertK]

Allright, the blocked cats are in the majority at this moment

It makes no sense to check the fuel delivery of both the fuel pumps ?

In that case I have an old spare cat from an E500 which I can put on my car. I do not know if this one is not clogged or good. It look likes more second-hand.
Do I have other good alternatives to replace the cat for an aftermarket one ? (keep in mind that I want the exhaust system as original as it can be except the cat in this perspective).

 

[gsxr]

Low output from the fuel pumps tends to be intermittent and generally has slightly different symptoms than what you describe. Unfortunately the only way to diagnose is to connect a fuel pressure gauge that is visible while driving, which requires investing in $200+ of gauge & AN braided hose. If the pumps are old/original, it would be wise to replace with new OEM Bosch, along with a new high-pressure OE/dealer hose (details here).

First perform the tests above to verify it is the cats. No point in planning exhaust changes if the cats are fine.

 

[RobertK]

Allright, takes some time to manage that. I will go for the first test (cross-pipe removal).

When the cats are clogged could it also be the reason that the engine coolwater temperature is raising at higher speed ?

 

[maw1124]

Allright, takes some time to manage that. I will go for the first test (cross-pipe removal).

When the cats are clogged could it also be the reason that the engine coolwater temperature is raising at higher speed ?

Short take is Yes because the exhaust heat isn't making it out the back of the car. But a drive with open exhaust will quickly show you the difference.

maw

 

[gsxr]

When the cats are clogged could it also be the reason that the engine coolwater temperature is raising at higher speed ?

YES!

 

[RobertK]

So, that is good news. Probably two big issues solved with one solution

 

[RobertK]

For certainty from my side this is the crosspipe I think (see below) ?

 

[gsxr]

For certainty from my side this is the crosspipe I think (see below) ?

View attachment 155026

Yes, that is the crossover pipe. Removing this temporarily will bypass the catalysts. And it will be VERY LOUD.

 

[sheward]

Note that driving the car for any extended period of time with this pipe disconnected can overheat the can box directly above it and render the car undrivable. I have not yet read about anyone experiencing this however I have had it happen Myself with a missing gasket at this joint. 15 minutes should be ok and long enough to wake everyone within a square mile.

 

[maw1124]

Note that driving the car for any extended period of time with this pipe disconnected can overheat the can box directly above it and render the car undrivable. I have not yet read about anyone experiencing this however I have had it happen Myself with a missing gasket at this joint. 15 minutes should be ok and long enough to wake everyone within a square mile.

Hell, one from zero to redline should tell it.

maw

 

[szvook]

@RobertK Before you start removing the crossover pipe, get the car on a lift and bang on the cats. If you hear anything loose inside, you’ll know for sure it’s the cats.

 

[RobertK]

@RobertK Before you start removing the crossover pipe, get the car on a lift and bang on the cats. If you hear anything loose inside, you’ll know for sure it’s the cats.

And that is the case, we bang on the cats and for sure we hear some loosen components inside so we quit the other test with removing the crossover pipe.
My decision is to put some new (aftermarket) cats on my car. I prefer stainless steel metal cats. A set of these should be fit on my car (see photos) according to the exhaust supplier. Better flow has been promised.
I want to let the rest of the exhaust as original as at can be and do not want a louder sound or so.

Is this a good choice ?

 

[maw1124]

Is this a good choice ?

Did (will) they tell you the brand name and how many cells? Looks like something off Ali-Express for $20.

Higher flowing cats (fewer cells) will flow better. Better flow will increase sound generally, unless I suppose the wall thickness is higher (I’m less certain of that), which I doubt these are. IIRC, I ended up with a Magnaflow 400 cell converter (2 of them), but I put a whole new exhaust on it. Not louder necessarily but certainly deeper in tone and weight savings. I think @gsxr and @szvook are probably closer to what’s being produced and sold today.

Cheers,

maw

EDIT… Magnaflow available from Summit Racing… https://www.summitracing.com/parts/mpe-59926?rrec=true
EDIT2… Fun 10 year old thread on related issues… Aftermarket "Performance" Cats: Worth the Trouble? | M119 Engine

 

[szvook]

@RobertK Maw makes a good point, do you know who makes the cats that you have in mind? You want to get good cats that have been in use for a while and from a good manufacturer. Magnaflow cats is a good choice and are priced well. Performance Industries and HJS make good cats, but they are pricy, especially HJS. Factory cats have 600 cells, so for better flow, 400 cell cats are the way to go, to keep the exhaust volume down a bit. Since the stock exhaust has the resonator and the larger muffler, 400 cell cats would not increase the volume that much. 200 cell cats would flow even better, but I’m not sure how loud the exhaust would be with them, as I never heard a stock exhaust from an 036 with 200 cell cats. Similar to Maw, my stock exhaust was replaced and I do not have the resonator or the large muffler anymore, and I went with 200 cell cats from HJS. But I wanted to open up the exhaust as much as possible and hear it. One of the reasons I went with HJS cats was me tracking my car on road courses and I wanted cats that can withstand the abuse.

 

[RobertK]

No I do not know the brand of these offered cats. If it is really Ali-Express quality then I have no interest in this ones. The Exhaust supplier asked 600 Euro for each of them. The manufacturer is from Belgium he said.

Other question: the Magnaflow cats Maw is referring, how can I see how many cells the Magnaflow 59926 type has ?
I will go for 400 cells.

 

[szvook]

For what’s is worth, those Belgian cats might be of good quality. But without knowing who makes them, it’s a gamble. The exhaust supplier should know who makes them.

As far as the Magnaflow 59926 cats cell count, just reach out to Magnaflow and confirm with them. Also, you might want to ask them how their metal substrate is being held in place inside the core.

 

[RobertK]

The exhaust supplier said also that these are racing cats used in sportcars. Supplier told also that for the 80 times he has fitted these ones, he only got 1 back where the core was loosened at the edge.

But I think I will go for the Magnaflow 59926. (by the way its containing 200 cells).

 

[szvook]

Cats to be used solely on a racetrack are usually 100 cell and are not made to last a long time. Majority of higher-end super cars will use 200 or 300 cell cats, i.e. - Ferrari, Porsche, Lamborghini, McLaren, etc, and they all use HJS cats, which only have a metal substrate for their 100, 200 and 300 cell cats.

Magnaflow does have a 400 cell cat - 54956, but that one has a ceramic substrate. You might want to ask Magnaflow if they only provide a metal substrate on their 200 cell cats.

​

 

[RobertK]

Alright, I will ask. If I choose for an HJS 200 cell cat, which type is suitable for my 500E ?

 

[szvook]

You would want the HD design. The core from HJS will have HD marking as well as the serial number: 5553692-01. I don’t have the part number, as I did not buy the cats from HJS directly.


There are a few ways to go about getting the HJS cats.

1. They have a dealer in the Netherlands. See if they have only the core, or if the cats already come with end caps.

KSC Import
De Sondert 13
5928RV Venlo
Netherlands
Email:
info@kscimport.nl
Phone:
+31 77 396 9824
Website:
www.kscimport.nl

2. You can find the dealers elsewhere in Europe - Find dealer

3. You can get the cats from Fabspeed - Fabspeed® | Performance Upgrades They are in the U,S. and that’s where I got my cats. Fabspeed has the cores and can weld on the end caps. Below is my invoice from Fabspeed and you can use their part numbers for the cats and the end caps. But since your exhaust is stock, as far as the pipes diameter (2.5 inches), you want to make sure you order end caps with the inlet size in and out with 2.5 inches, so the part number for the end caps might be different. The invoice shows 2.75 inches because my exhaust was modified to a 3 inch diameter.


Btw, the HJS cats will not have an issue with EOBD or MOT inspections. Not sure if these inspections apply in your area, but in case they do, you’ll be ok.

 

[RobertK]

Thanks Szvook, I wll go for the HJS. I can buy only the core and then an custom exhaust specialist (with very well TIG welding) can make it in the most desirable way in welding the end-caps etc. (no bents etc.)

 

[szvook]

You are quite welcome, it’s the least I could do. Btw, the HJS cats have a directional flow. So when being installed, you want to make sure the arrow on the cores is pointing towards the rear of the car.

 

[RobertK]

One question about putting the HJS kats (200 cells) on my car:
This has not negative or bad consequenses for the (now very good and smooth) running of the engine ? A mechanic at MB Classic Center in Hilversum (in The Netherlands) said to me that these engines need some backpressure and putting other kats could have bad influence on the smooth running and performance ot the engine, also less torque at lower rpm's. Is that true ?

 

[gsxr]

A mechanic at MB Classic Center in Hilversum (in The Netherlands) said to me that these engines need some backpressure and putting other kats could have bad influence on the smooth running and performance ot the engine, also less torque at lower rpm's. Is that true ?

No. Mercedes sold the 500E (and other M119's) in some markets without catalysts (non-KAT). The engine does not "need" backpressure. Typically there is a small (single-digit) increase in rated power without cats.

 

[szvook]

No offense, but I would question that mechanic’s knowledge as a whole.

 

[RobertK]

Good news !
Problem with the bad performance is solved. New cats installed and it runs much, much faster and better.
The old cats were totally internal destroyed. MOT also not passing because of too high CO yesterday with the old cats.

 

[RobertK]

Thank you very much for your help and useful information guys, I forgot to say

 

[szvook]

@RobertK Great to hear. Btw, are those 200 cell cats also from the same Belgian manufacturer? Do they have a metal substrate? How does the exhaust sound with these cats?

 

[RobertK]

No, this is of a sub-brand of HJS. I do not know the name. The HJS supplier offered this as equal quality. Same make and structure and material. It looks like also the same. For the difference in price I'll take the risk.

I am happy with the sound. It is almost the same and not louder.

 

[RobertK]

I had never expected such a different in performance between that original defect, clogged, internal seperated cats and this one. It is like if I have an other car. So much faster, also in lower RPM's.

I think that my heating problem at high speeds is also solved but I have to test that when I have the oppertunity to do that:

Temperature raising while driving fast | Heating and Cooling

I have a question about the following: After replacing my thermostat (the old one was a bit of lazy) the temperature is raising when I drive faster: For example: 180 km/ph it raises to 100 Degrees 190 km/ph it raises to 105-110 Degrees 200 km/ph it raises to 115 Degrees When I drive in the city...

www.500eboard.co

 

[maw1124]

Good news !
Problem with the bad performance is solved. New cats installed and it runs much, much faster and better.
The old cats were totally internal destroyed. MOT also not passing because of too high CO yesterday with the old cats.

They look good. Congrats!

Yes, that’s the way she’s supposed to breath. I’m certain the high temp issue is solved as well.

@RobertK it would be nice to know who made the units, with part numbers if possible.

maw

 

[szvook]

Clogged cats could definitely play into higher engine temperatures. With a higher increase of exhaust pressure that is somewhat stuck, the exhaust manifold could start to overheat and trap the heat.

 

[szvook]

@RobertK Did your heating problem at high speeds go away now?

 

[RobertK]

Yes, I have noticed that the temperature needle stays on the same spot (84 degrees) during speeds above 200 km/per hour during several minutes or more. At all circumstances it stays on 84 degrees by the way. Problem is solved !!

When selling it to a Cats recycle firm we noticed that one of my old cats had lost half of its ocntent.

 

[maw1124]

When selling it to a Cats recycle firm we noticed that one of my old cats had lost half of its ocntent.

... and the other half was plugging the remaining cell flow...

maw

 

[szvook]

Yes, I have noticed that the temperature needle stays on the same spot (84 degrees) during speeds above 200 km/per hour during several minutes or more. At all circumstances it stays on 84 degrees by the way. Problem is solved !!

When selling it to a Cats recycle firm we noticed that one of my old cats had lost half of its ocntent.

Great to hear. Btw, how many miles were on the those cats? Were they ordinal OEM?

 

[RobertK]

My car has 71k miles on the odo and had the original OEM Cat. It was 29 years old but a little bit strange after such a less amount of miles.

 

[szvook]

Does (or did) your car run on the rich side? Too rich and the cats can get damaged to a point where they can start to melt down, which “could” explain why one of cats lost half of its substrate. On the flip side, if those sub-brand of HJS cats have the same metal substrate as the HJS HD cats do, that metal substrate can handle a bit more heat than a ceramic substrate can. Up to 1050 celsius on their metal substrate vs. 800 celsius on a ceramic substrate. Btw, when was the last time you checked your spark plugs?

 

[gsxr]

Another possibility is a physical impact to the cats from below. Once the substrate is cracked or damaged, it can get progressively worse. There may be *very* little external evidence of an impact, making this difficult to verify unless there's an obvious dent in the bottom of the housing.

 

[szvook]

+ 1. @RobertK When you initially got the car, did you inspect it from underneath?

 

[maw1124]

Mine were rattling at 60k miles, but I also had a RENNtech eProm (PO) which I'm almost certain encouraged a certain amount of rich running during warmup at least. Car also ran the One Lap of America Race (also PO), so those were some "hearty" 60k miles.

maw

 

[szvook]

Just to provide some context, my OEM cats were replaced with 126K on the clock and they were ok.

 

[RobertK]

Could be the case that there were some problems with the mixture as a cause of my LH-module problems. Or the external impact issue what Gsxr said could be the case, visually I saw no damage or something, we will never know.

The engine runs well and my spark plugs are renewed for the MB OEM Beru's two and a half year ago (8k Miles since then)

 

[dionphaneuf]

Looking online and basically every exhaust pressure tester is some version of this one. Seems fine in that it clearly shows >3psi as bad but wish there was a nicer one out there. Suspect my cats are clogged...stumbling at idle, issues at load. Will pull codes again and research more and post full story in a more appropriate forum but I'm thinking it could be clogged cats and so this belongs here.

https://www.amazon.com/Exhaust-Back-Pressure-Tester-Gauge/dp/B09WTZRL8N/