Loss of power at 4.5k

[Germain]

I know I have read posts about this before, but performing a seach for "High RPM", "Loss of Power", ect. got me nowhere.

Heres the deal, just did tune up, points, timing ect. and car is running much much better now. Only thing is at about 4.5k it flat lines, I feel no power. Any ideas of whats happening here? Thanks

Kevin Germain

[iustasail]

What type of setup do you have? Carbs? D-jet?

[neilca]

Are you running a rotor button with a rev limiter? These things have springs in them that can get weak thus causing it to limit to a lower RPM.
Good luck,
neil

[Germain]

hehe, well one should be more specific when asking questions eh?

I have a 1973 2.0L, stock F.I. with stock Dist. No fancy stuff, just points and a big blue coil.

Now, I have no idea about a rev limiter, how would I know if I have one? Everything looks stock, and I see no additional wires running to anything weird or out of place...

Thanks all for the help.

[Joe Bob]

You did not say if this is a new thing...the loss of power....when I got my first 1.7. It had been sitting for quite a while. It had a crappy Monza exhaust.....took it off used it for a boat anchor and installed a Bursch....

[Germain]

This is a new thing, well sure. Quick story I got the car 2 years ago, it was sitting in an open field for years here in MI. I towed it home and have replaced the tranny and "read end". No engine mods, just started it up. I have the "crappy" Monza exhaust, but no boat, I however don't think it could cause this kind of performance lag. Its like a fuel supply sortage or spark problem, but I can't find anything wrong.

[John Rogers]

Try new FI points. This happened to my daughter's 914 and the new set of FI points cured it. Good luck.

[Germain]

By FI points I'm assuming you mean the points in the dist...

[oredith]

on the rev limiter..
here's a stock one http://www.pelicanparts.com/catalog/images/ignition/914_rotor.JPG
the one with the built in rev limiter is a lot bulkier.. i can't remember where a picture is, but if it doesn't look like the one from above, chances are it's a rev limited rotor. if it has been sitting around as you have described it, that *could* be the problem.. in that case, a quick couple of bucks for a new rotor will tell ya if it's the culprit..

[oredith]

and you might want to pick up a fuel pressure gauge too while you're at it.. 20 bucks for the gauge, probably a lot cheaper if you just find a generic gauge that reads 0-60 (you want the reading to be at the midrange [30]) and another 5 for the t-fitting & hose clamp. it's nice to have a constant monitor of the fuel.

[Joe Bob]

I think he meant trigger points when talking FI points....they last 80-100,000 miles. But when they go, they fade away....on the Monza thing, it would not let my engine tach past 4,000 rpm. Crappy even for a 1.7. The Bursch allowed it to rev to 5800 and beyond when going down hill...8^)

[Germain]

Really? Please give me more detials on the exhaust stuff. Why would the Monza not go past 4k but Bosche do 5.8? I'm asking because I am wondering about this part of the engine. I had no idea this could have a large impact. Thanks for the info everyone.

[Joe Bob]

Because the Monza/boat anchor had really small ID on the pipes. I don't know if the pipes had corroded or if they came that way.

When compared next to each other....the performance, it was night and day...the other benefit was the exhaust tone....before it sounded like a handfull of nickles in a coffee can, the Bursch sounded a little more like a sporty car instead of VW on Percodan....8^)

[JTB]

If you have a Haynes manual, check out page 63. It shows both distributor rotors. The speed limiting one has a spring loaded plunger that will ground out the spark when centrifugal force overcomes the spring.

[iustasail]

If your Monza exhaust is to restrictive it will cause to much back pressure. Combine this with a restrictive intake system, ie. D-jet, with its small throttle body and spaghetti intake piping with it's multiple 90 deg bends etc... and you get an engine that can't get enough air to burn all the gas. The stock 2L exhaust has quite low restriction, I noticed a significant improvement in my 1.7 over to old headers and monza combo.

Exhaust does make a difference but you may want to play with the dwell and advance a little. If the spark comes on to late the pistons will have traveled through much of their power stroke with no explosion!

There is a fine line between to much advance and not enough advance if you are looking to get the most out of these engines.

I suggest that you get a pressure reading on the fuel system.

Do the injector flow test.

Forward the advance some and drive the car and see if it backfires when you come off the gas. If it does retard the advance a little and try again. I found that the factory spec was to mild for my car and I did not get the top end I wanted.

Do you have a vacuum advance? if you do and it is not working well then you may have found the problem! Mine took some work and once returned to smooth operation with good hoses I noticed a big difference.

[AlexO]

My 2.0 used to do basically the same thing. I think the major culprit on my engine was the centrifugal advance was siezed. I would check that, the condensor ground, and the point gap. Hopefully that should clear things up.... Good luck. BTW I was using a boat anchor as an exaust at this point....

[Germain]

Well I've tried everything I can think of, and now things have gotten worse. I have a good dwell reading, I'm waiting on the Crane 700 thingy to replace my points and see if that helps. Now the car cuts out, misfires, between 2-3 rpm's when its hot. Any more ideas?

[Dave Bell]

More Ideas....

Have you checked the fuel pressure and fuel pump? I have recently had a new problem, yesterday morning the car would not start.. fuel pump was not running... checked the power connections to the pump, moved it and it started... probably some kind of loose wiring which I have to dig into tonite or tomarrow... drove my daughter to school and had rough running... the loose wire was probably on and off to the pump.

On an old Honda Motor cycle, many years ago I had a loose connection to one of the coils... that only "vibrated" on/off at higher RPM and caused loss of high end power. It took me 1 month to figure it out... that after I had broken down both carbs, cleaned and put them back together.

In short... look for some loose intermittent connections that could be on/off when things get to vibrating... not that those things are easy to find but it is another idea that I have experienced in the past and am experiencing today!

- Dave

[Germain]

Well, it seams as though the cutting out was caused to a intake valve clearance too large. Valve wouldn't open enough. Now Im just waiting on my pointless system to come in and see if it fixes the high rpm problems

[Germain]

Well now, I didn't get the new pointless system yet, but the problem went away. I think its electrical now, but what???