P38A V8 (4.6) rattly under acceleration and a bit lacking in ‘oomph’

Hi, and sorry to
Bother you again with what is likely a daft question.

My ‘97 P38 4.6l Gems has been ‘resting’ for a wee while and I finally got her up and going today.

all seemed ok but I noticed a distinct rhythmic metallic rattle under acceleration and what felt like a corresponding lack of ‘grunt’.

oil and fluids seem ok, maybe could do with some more fuel in her but is there anything I should be looking for in particular ? <yes, it’s a rover V8, where do we start…>

from memory she used to sound as sweet as a sewing machine and pulled effortlessly.

thanks for any insight you can offer -I’m Really out of my depth with this one !

Bob

Rattly? You mean pinking/pre-ignition?

I don’t know, I had the window down and when I put my foot down it sounded ‘off’.

the noise was very like an air-cooled VW now that I think about it (if that makes sense)

battery has been out but I’ve not been messing with anything engine-related.

I did pop some Redex in the tank as it’s her MOT tomorrow -I wonder if it could be that ?

Unlikely redex.
Is it popping back through the air intake? That started for me under acceleration, then got worse over time. Check the colour of your plugs

I should check the air intake is all properly back together, I had taken the cover off for some reason and ought to check the join at the Mass air sensor.

I do actually have some new plugs to go in, maybe I should look at that before the test

With all the plugs out spin the engine over, and see if you can hear any rattles or anything else obvious. If you bridge the starter relay instead of using the key, the fuel pump wont run, so less fumes !! Did my rebuilt engine like this to check oil pressure, etc before starting for first time.

Or just take the relay out

Your cats have gone.....simple.

Hmm.. the exhaust has definitely seen better days -although it did odd an MOT emissions test today.

I will need to look into a replacement and I supose that Stainless is the way to go… $$$’

Bad cats is a bit extreme imo.
Start at checking the air filter condition and work your way towards the airflow sensor MAF (connection and/or needing cleaning or replacement),
check condition of HT leads and being securely connected to spark plugs and coil packs,
check all spark plug conditions and gap (.040” +/- .002”).

If you have a diagnostic tester this will help immensely to monitor fuel trim readings, engine timing, air flow sensor MAF pressure/voltage, engine cylinder misfires and roughness, O2 readings, fuel pump operation, petrol tank pressure and other precise readings.

I have nanocom.

will have a look and post the results to
See if there’s anything amiss

awkwardbob said:

I have nanocom.

will have a look and post the results to
See if there’s anything amiss

Click to expand...

check for rough running on a cylinder, you wont get zero on all 8, but occasional low numbers is normal

The rattling is the clue get under the car a give each cat a thump with a rubber mallet

Gently,I hope !

like I said, the sound was almost identical to an air-cooled VW, a bit ‘whirry’ if you know what I mean.

awkwardbob said:

Gently,I hope !

like I said, the sound was almost identical to an air-cooled VW, a bit ‘whirry’ if you know what I mean.

Click to expand...

can you record it?

My cat rattles a bit when hit with a mallet. Still he catches mice & stops others crapping in garden !,

Here you go,

V8 sounding like a VW at about 20 secs in.
Hoping it’s *just* something exhausty

https://www.dropbox.com/s/4m4lisfku9xq48s/V8 VW.m4a?dl=0

This link may not work so will try another

doesnt worky
asking for single sign on

Try this link, shoukd work for anyone with dropbox

https://www.dropbox.com/s/yhrrncpabk2dsjg/V8 VW.m4a?dl=0

That sounds diesel like