Stalling and bunny hopping

Evening I have a 1992 sportline and the first time it had been out in the hot weather - I know I need an new exhaust which I arranging and it's making some funny sounds however today the car stalled 3 times not all the time and then started to bunny hop when accelerating and there is a "blowing noise" which could be the exhaust making the drum hum - any pointers ? Could the exhaust cause these issues or fuel / air issues 

Carb or injected?

Injected 

Just to add yesterday I cleaned the car and also waited until it warmed up then I heard the blowing sound again, but this morning I drove it to the paint shop and it was fine no bunny hopping or noise - just wonder if when its warm ?

Blowing sound?  Where front, rear, left, right.  What was the temp gauge showing, how warm was the oil
The only thing I can think of is the radiator fan… for blowing noise.

As for the hopping, well fuel pressures and possible brake issues as in the rear cables aren't fully releasing causing brake drag, and over heating of the rear drums.

Bad motor mounts which can cause exhaust pipe beating on things more of a drumming than a blowing noise.  Large holes in the exhaust or clamps that are loose as as the pipes get hot and expand allowing gasses to exfiltrate joints.

You leave a lot to be desired in narrowing down the noise, as also is it in the engine bay and which side of the engine that it is coming from, the air box can make noise is not properly seated, and sealed.  Vacuum leaks
at the air hose that connects the MAF to the Throttlebody and that hose having weak spots, or holes in it, which allows unmetered air.

We can help you narrow it down with more details.

Hi mate, sorry I was rushing to post that, and I should have given you more information - apologies - l will try and break it down…

The loud blowing sound comes from underneath the car/back of the engine bay, when the car gets warm it like a horn blowing, and increases when I change gear - the temprature is good, fan comes on and is quiet- I think it is from the exhaust as directly under the car when opening the drivers door and its idle, hearing a rattle sound.

Blowing noise comes from around the top left of the engine (if looking under it directly) past the rocker cover but underneath.

The weird thing is I got in it today and it was fine no blowing and no bouncing, but I did move it straight away from starting so I wonder if its heat related as didnt get up to temp and didn't experience the bunny hoping…

The car itself is sort of a barn find, as the previous lady owner had it for 28 years and never drove it, and it defo needs a new exhaust which is my first port of call, however its in the body shop at the moment to get the bumpers done etc

I just wanted to know if a dodgy exchaust could cause this and I think you have confirmed that when it gets hot it could…

Well my experience with 90 cabriolets, and I have had 3 of them.  The Exhaust manifolds are a very poor design.

All of mine Cracked, one Whistled like an air cooled
The other hissed, and the last one was so bad it failed emissions as there was probably more exhaust coming out of the cracks than the tail pipe.

I opted for the G60 4-2 tail pipe and dual down. it took care of all of my problems….

The first manifold and dual down I bought from tt tuning over here, and it was about 400USD + shipping.  The Second one I bought from a junk yard or Breakers, 30 bucks, and I had the dual down built by my muffler guy and that was another 40….  

Hard to say but could of quick things to try - if it’s got stale fuel in it (and you don’t/can’t get it out, trying filling her all the way up with something good like shell v power to try and dilute the old stuff down. Could Chuck in a fuel cleaning additive to the tank too.
May be timing so there’s plenty of posts on here from far more knowledgeable people than me showing how to adjust/rotate the dizzy cap to change that. Or use a timing gun.

Fuel lift pump inside the tank can cause cutting out and bunny hopping if it's on its way out, the main fuel pump underneath the car will get louder when the lift pump fails. I've had my lift pump randomly fail serval times before it gave up completely.
 Have a look in the fuel tank and check for rust and dirt when removing the lift pump and sender.

I guess your car is k-jet fuel injection and not digifant?

I would assume from your description that it's "bunny hopping" because you are trying to drive it when it's mis-firing. This could be caused by a thousand and one things.

I would get the exhaust done and then get it serviced, then you can look into the misfire from there.

Yes jazzydog is right as just re read your posts and the car is a barn find…
what have you done and changed to get it running and have you looked in the fuel tank and flushed out any old fuel as it goes off after about 6 months…

Thanks for all the feedback - I wanted to elborate when I say "sort of barn find" the previous lady owner had it for 28 years, never took it out of her garage when raining, and never drove it at night - only time she used it was to run her grand children to school and that stopped many years ago - she has been using it but the MOT History is like 50-100 per year….

I purchased it via a classic car webste and had it trailered to me, I have done history on the car, and investigation, and I believe it never had a service because the lady only put it in for MOT and then when stuff needed to be fixed it was fixed (e.g new fuel pump etc) - however I have had an indy VW speaclist look over it and the comments "honest" and "in good nick" and "seen worse" were muted - I know from delivery of the car the exhaust needs replacing.

I have a 4 Phase plan for the car, Phase 1 Secure it/Stereo (Done), Phase 2 Mechnicals / Service, Phase 3 new Roof (done) and Phase 4 Body Work (done).

The Indy guy is currently on holiday so I am waiting on a ramp at his place when he returns and will hand it over and say there you go for a complete service.

My post was more to identify if the exhaust would cause this issue, blowing (naturally yes) but the bunny hoping, and it only happens when it was really hot.

Appreciate all the feedback - and this is my first Mark 1 so grateful of the responses.

Could it be bad fuel if it's been standing or water in the fuel, corroded fuel filler neck possibly? Did you jet wash the drivers side rear wheel arch? Check the fuel filter, and pour fuel contents into a jar check for colour and water, worth changing filter anyway. If ordering new fuel filter (it's on the right side of metering head near battery). Check you get the correct size filter, sportline has larger fuel filter.

If you remove the fuel filler cap and shine a torch down the pipe and look for any rust or holes.

I hole in the fuel filler neck will kill the injection system in no time and replace parts, servicing or getting someone who understands it as garages can't use a laptop to fault find is getting harder…