Engine will not rev past 4000 RPMs

[kmpdx]

Hey guys. I was on the freeway and realized that I was not getting any power. I pulled off and did a quick inspection and didn't really see anything obvious. I drove home and the car starts and begins acceleration fine but in any gear 4000 RPMs seems to be the max is gets to and then it just won't go past 4000 RPM. I plan to do more to diagnose it this weekend but anything jump out to you guys? Fuel pump? Thanks.

[Sapper 157]

First thing I would check is your throttle linkages. Make sure the cable is not excessively loose

Edited February 9, 2018 by Sapper 157

[Knucklehead Saloon]

Is it doing anything else at the same time like getting hot or popping/ backfire or making weird noises ?

[kmpdx]

Not getting hot, not popping. No weird noises. I still need to go out and check the accelerator cable. I am in nursing school and can't check it until Saturday. I will drive it around and get a better diagnostic. Thanks.

[naru]

Restricted exhaust.

 

Bad fuel pump would give a sputtery type power loss

[jono]

restricted air filter is anther possibility, to consider as well as the ones above

 

any service history to report, or have you just driven it the last few years and done zip?

[kmpdx]

So I did a qucik look and noticed the cv axle seal where it plugs into the transmission on the passenger side is leaking. I did not have time to check the fluid level yet but if it were low could that cause this? I will do thorough troubleshooting tomorrow to get more information.

 

What I did most recently was add a fuel addirtive that is supposed to clean the fuel system. It was a Lucas brand one but I don't remeber exactly what .

 

I have done routine stuff includinngrebuilding the cooling system, belts, air filter, regular oil changes, among other things in the last year so I am pretty in tune with the car.

 

I will check it out better tomorrow. Thanks for all the suggestions.

[subnz]

if it has a distributor it could be the centrifugal weights  / shaft could be at fault  that advance the ignition timing   - it  may not be advancing ignition timing enough   or ignition timing also could be retarded  (sluggish acceleration and backfiring if really retarded)

Edited February 10, 2018 by subnz

[DaveT]

Low level of gear lube in the diff won't bog it down.  It will eventually ruin the gears and pinion shaft bearings.

[czny]

How many miles on this engine?

 

Weak or broken valve springs will limit engine performance. If it were a broken spring you'd notice a sudden performance change.

Weak springs develop over time.

[subnz]

If it has a carb the 2nd choke  - this may not be opening /working

Edited February 10, 2018 by subnz

[czny]

If it has a carb the 2nd choke  - this may not be opening /working

Look at his avatar - 1991 Loyale. More likely SPFI.

[kmpdx]

Hey guys,

 So to answer a few questions, 1991 SPFI 1.8L Loyale manual transmission w/212k miles on the odometer. 

 

I pullled the air filter and plastic boot and checked the butterfly valve, confirmed that the accelerator linkage was fully functional, and pulled the fule filter and checked that it is clear. Transmission fluid is fine.

 

I drove it around and starts fine and accelates fine for a while. Then under load and uphill it just quits geeting power. If I let off the gas and wait a second I can get it to gas again but it never reaches full power. It does seems to max out RPMs in third but can get more in lower gears intermitently. WHile I can not rule out the valve springs being the problem, it is not as consistent as I would expect.

 

I really am leaning toward resricted exhaust at this point. When I drove it around I stopped at the auto parts store, there was smoke coming off the exhaust manifold. Due to oil leaks this would not be unusual but it was quite a bit. When I looked under the car, there was smoke coming out seams where the front exhaust converter meets the pipe and at the seams in the catalytic converter. I also feel like the motor sounds like it is restricted.

 

The guy at the auto parts store said to diagnose this I should pulll the O2 sensor and see if it has the same problems. Does this sound like the best thing to do at this point? Anyhing else you guys think I might try?

 

Thanks, 

kmpdx

Edited February 10, 2018 by kmpdx

[subnz]

If the exhaust / cat.  isn't restricted

Another thing to consider that  if your car has a traditional ignition set up,  like the earlier EA82s ie distributor / coil ignition .

The ignition coil could be faulty - they do funny intermittant things when failing,   especially under load and when they warm up

Edited February 11, 2018 by subnz

[kmpdx]

Subnz,

I am going to test the coild and distrubutor cap to rule those out. Proabably won't get to it until next weekend. 

Thanks!

[subnz]

The high tension leads ie  1   coil to  distributor and the 4 cap to spark plugs leads  could be tired also  - wouldn't hurt to replace these. (can break down under load and when get warm also  - similar to a failing coil)

As you mentioned - check condition of distributor cap and rotor as well.

.

 

Also as I suggested in previous post here,  it would be worthwhile taking the distributor apart  ie taking off the plate holding coil/s and check the operation of the centrifugal advance  weights and shaft (perhaps sticking needing lubrication , located under this coil plate) and the operation of the vacuum advance unit  as well. 

 

It may be  easier to take the  distrubutor out to do this, but before removing -   leave rotor on and mark exact position its pointing to (with tipex or  whiteout is good) so that when replacing it, the rotor is in the correct position for ignition timing.

You will have to reset ignition timing if removing / moving distributor and or removing coil plate  - with timing light (  20 degrees BTDC for SPFI  -  timing light on no.1 lead)

Edited February 12, 2018 by subnz