Please help! Run out of ideas for strange loss of power

  • Thread starter Mr Maui
  • Start date
  • Watchers 8
M

Mr Maui

Joined
Apr 7, 2020
Messages
22
Location
UK
Hello!

Firstly thanks for clicking on this thread - I love my cruiser and use it every day for work and fun, but its had a problem with it ever since I have owned it.

1fz-fe - 4.5 24v petrol 1996 (OBD1)

First start up and pull away its perfect, pulls lovely drives smooth. Within a few minutes it starts to struggle below 2.5k revs. Loss of power and you have to floor it back to above 2.5revs to get it to run nicely. Then when travelling at speed it feels like its being retarded, slight pull back every minute or so almost like you are letting off the gas, this only happens between 2 and 3k revs. After a few miles this stops and it will drive lovely all day, idles fine, low revs fine....

EXCEPT - when you stop the engine and start again, you almost can't pull away, it really struggles and will stall if you leave it idle for more than a few seconds. Once you pump the gas and get it to rev above 2.5k it then corrects itself and will run fine again until you next stop it

Its had a -

new head cylinder this year (Gasket gone)
OEM knock sensors replaced
OEM O2 Sensor (Only got 1 pre CAT)
PCV done
Filter change
MAF cleaned
All exhaust joints have been checked for leaks


I am pretty sure it is electrical and am now thinking could it be and faulty wire from either knock sensors or the O2 sensor??

Other than that I am a loss...... And not keen to throw more money at it without a good reason.....

Any help would be much appreciated

Silas
 
paulzak

paulzak

Joined
Dec 27, 2012
Messages
165
Location
Sonora, CA
Could be something as simple as ignition wires, cap or rotor. You could try poking the wires gently with a well insulated stick and see if there is a change.
 
M

Mr Maui

Joined
Apr 7, 2020
Messages
22
Location
UK
Not sure how to check timing??

Regarding wires and cap - do you mean the spark wires? Just wiggle them about?

Cheers
 
gummycarbs

gummycarbs

Joined
Apr 14, 2016
Messages
1,319
Location
Oregon
Then when travelling at speed it feels like its being retarded, slight pull back every minute or so almost like you are letting off the gas
Sounds similar to my experience with a bad throttle position sensor.
 
Wrencher93

Wrencher93

Joined
Apr 17, 2018
Messages
1,066
Location
Roanoke, VA
Check your catalytic converters. Some of the catalyst had broken loose in mine and it would have intermittent power loss based on how the loose chunk was positioned and blocking exhuast flow.
 
M

Mr Maui

Joined
Apr 7, 2020
Messages
22
Location
UK
Thanks for the responses - will look into the TPS - just ordered a new one - looking at it the screws holding it in are non standard and pretty mullered! So this could be the culprit.

Will have search for how to set these up - any tips or just position until it idles nice?
 
M

Mr Maui

Joined
Apr 7, 2020
Messages
22
Location
UK
I have ordered one!
 
Crinkler

Crinkler

SILVER Star
Joined
Nov 2, 2018
Messages
166
Location
Michigan
Wrencher93 nailed it! go under your truck (not when hot, dont want to burn your hand) and bang on the exhaust converter. if it sounds like a can of rocks then this is your problem.
 
BILT4ME

BILT4ME

Joined
Nov 9, 2012
Messages
11,783
Location
Olathe, KS, USA
Hello!

Firstly thanks for clicking on this thread - I love my cruiser and use it every day for work and fun, but its had a problem with it ever since I have owned it.

1fz-fe - 4.5 24v petrol 1996 (OBD1)

First start up and pull away its perfect, pulls lovely drives smooth. Within a few minutes it starts to struggle below 2.5k revs. Loss of power and you have to floor it back to above 2.5revs to get it to run nicely. Then when travelling at speed it feels like its being retarded, slight pull back every minute or so almost like you are letting off the gas, this only happens between 2 and 3k revs. After a few miles this stops and it will drive lovely all day, idles fine, low revs fine....

EXCEPT - when you stop the engine and start again, you almost can't pull away, it really struggles and will stall if you leave it idle for more than a few seconds. Once you pump the gas and get it to rev above 2.5k it then corrects itself and will run fine again until you next stop it

Its had a -

new head cylinder this year (Gasket gone)
OEM knock sensors replaced
OEM O2 Sensor (Only got 1 pre CAT)
PCV done
Filter change
MAF cleaned
All exhaust joints have been checked for leaks


I am pretty sure it is electrical and am now thinking could it be and faulty wire from either knock sensors or the O2 sensor??

Other than that I am a loss...... And not keen to throw more money at it without a good reason.....

Any help would be much appreciated

Silas
If I was to guess, it would be related to cleaning the MAF.

Which MAF/AFM do you have? Since yours is a 95, it should have a MAF, but since it is OBD1 and not USA market, it could have an AFM. If so, it's possible someone removed the two screws and yanked on the harness and junked your AFM.

Please post a pic of the AFM/MAF under the hood.
 
RAYJON

RAYJON

Get a bigger hammer..
Joined
Oct 20, 2005
Messages
1,940
Location
Reno NV
fuel pressure, filter-fuel pump Is my guess, if the motor goes lean it will pull timing ,

like others have said I would check spark first, if you pop the hood at night and there is a light show between the plug wires you have issues. Aftermarket wires don’t seem to last long on a 80.. spark plugs will tell a story, pull and look at them. if they look lean then I would go after the fuel pressure..

on the plugged catalyic converter/ muffler heat Gun will show if it’s plugged.
 
M

Mr Maui

Joined
Apr 7, 2020
Messages
22
Location
UK
If I was to guess, it would be related to cleaning the MAF.

Which MAF/AFM do you have? Since yours is a 95, it should have a MAF, but since it is OBD1 and not USA market, it could have an AFM. If so, it's possible someone removed the two screws and yanked on the harness and junked your AFM.

Please post a pic of the AFM/MAF under the hood.
It's a MAF, I did take it and spray with cleaner which improved general response but no different to the current problem

IMG 20211004 110427 679
 
M

Mr Maui

Joined
Apr 7, 2020
Messages
22
Location
UK
Wrencher93 nailed it! go under your truck (not when hot, dont want to burn your hand) and bang on the exhaust converter. if it sounds like a can of rocks then this is your problem.
Gave them both a good shake and pretty silent. A very slight rattle but nothing major. Joint sealant used on the flanges, I've heard these can clog the insides?
 
Wrencher93

Wrencher93

Joined
Apr 17, 2018
Messages
1,066
Location
Roanoke, VA
Gave them both a good shake and pretty silent. A very slight rattle but nothing major. Joint sealant used on the flanges, I've heard these can clog the insides?
Well, I'm no expert on exhaust systems but I will say that the factory cats on an 80 are heavy SOB's so "jiggling" them might not guarantee that nothing is loose. When I removed mine with a Sawzall I was surprised at how chunky they were. Mine were also completely clogged so there's that. Don't let my suggestion lead you down the wrong path, though. It was just something to put on your list if nothing else seems to make sense.
 
M

Mr Maui

Joined
Apr 7, 2020
Messages
22
Location
UK
FIXED!

Firstly a huge thank you to everyone who helped me with this problem I changed the TPS and set it up as the manual and the truck now drives beautifully is like a new car

If only I had tried this earlier in the process!
 
M

Mr Maui

Joined
Apr 7, 2020
Messages
22
Location
UK
NOT FIXED

ok so 2 day and it's doing it again. First start up runs perfect. Once warm and you switch off. It then will barely move and stall untill you manage to get it above revs, then it drives lovely

Something about start up and being warm....
 
too tall

too tall

Joined
Jan 9, 2004
Messages
1,677
I agree with RAYJON , I would try to monitor the fuel pressure and see if it does anything weird during or after the warmup cycle.
 
M

Mr Maui

Joined
Apr 7, 2020
Messages
22
Location
UK
I agree with RAYJON , I would try to monitor the fuel pressure and see if it does anything weird during or after the warmup cycle.ow would I monitor the fuel pressure with an OBD1 vehicle?
Away for a few days but will carry on investigating when back - how would I go about monitoring the fuel pressure on an OBD1 truck?
 

Users who are viewing this thread

Top Bottom