Cutting out?, in higher rpms. Ignition problem or Mixture? Options

[749142]

Replaced 1.8 heads on my 1.9 engine with 2.0 heads. Runs good up until about 4600rpm and and then it will cut out. wth. any thoughts?

[ericread]

Obviously it's got to be fuel, spark or mechanical. From your post, nothing points to mechanical as there should be nothing magical between 4400rpm and 5000 rpm.

Fuel? Could be a fuel starvation problem. But it doesn't sound like that to me. Is it sputtering or a real drop in power? Maybe you should put a pressure gauge on your fuel rail and bring her up to 5000rpm. If you see a significant pressure drop, you know where to look.

Anyway, assuming this is a stock setup with stock FI, it appears to be electrical. At the higher rpms, the dist is spinning pretty fast and a cracked dist cap or some such nonsene can cause significant power drop over 4000 rpm. In my case, even though there was no indication of a problem with the cap, a new dist cap completely resolved upper rpm power loss.

But first of all, isolate it to fuel, spark or mechanical. You;ll save your self some time. (IMG:style_emoticons/default/idea.gif)

... And let us know more about your setup.

[749142]

Obviously it's got to be fuel, spark or mechanical. From your post, nothing points to mechanical as there should be nothing magical between 4400rpm and 5000 rpm.

Fuel? Could be a fuel starvation problem. But it doesn't sound like that to me. Is it sputtering or a real drop in power? Maybe you should put a pressure gauge on your fuel rail and bring her up to 5000rpm. If you see a significant pressure drop, you know where to look.

Anyway, assuming this is a stock setup with stock FI, it appears to be electrical. At the higher rpms, the dist is spinning pretty fast and a cracked dist cap or some such nonsene can cause significant power drop over 4000 rpm. In my case, even though there was no indication of a problem with the cap, a new dist cap completely resolved upper rpm power loss.

But first of all, isolate it to fuel, spark or mechanical. You;ll save your self some time. (IMG:style_emoticons/default/idea.gif)

... And let us know more about your setup.

it does have stock djet fi. ive tried different caps and such nothing changes so maybe something else ignition or like you said fuel. but i think its ignition because the tack will surge at times.

[orange914]

Obviously it's got to be fuel, spark or mechanical. From your post, nothing points to mechanical as there should be nothing magical between 4400rpm and 5000 rpm.

Fuel? Could be a fuel starvation problem. But it doesn't sound like that to me. Is it sputtering or a real drop in power? Maybe you should put a pressure gauge on your fuel rail and bring her up to 5000rpm. If you see a significant pressure drop, you know where to look.

Anyway, assuming this is a stock setup with stock FI, it appears to be electrical. At the higher rpms, the dist is spinning pretty fast and a cracked dist cap or some such nonsene can cause significant power drop over 4000 rpm. In my case, even though there was no indication of a problem with the cap, a new dist cap completely resolved upper rpm power loss.

But first of all, isolate it to fuel, spark or mechanical. You;ll save your self some time. (IMG:style_emoticons/default/idea.gif)

... And let us know more about your setup.

it does have stock djet fi. ive tried different caps and such nothing changes so maybe something else ignition or like you said fuel. but i think its ignition because the tack will surge at times.

surge also?... what about a blocked fuel filter or even weak fuel pump, sounds fuel related over spark if both surge and high r.p.m. (flow) are the same issue

make sure of good flow/pressure

[ericread]

Time to put a pressure gauge in your fuel rail. Let's see if the fuel pressure changes between idle and 4000 rpm. That would point to the fuel filter/pump issue as described above.

[749142]

Obviously it's got to be fuel, spark or mechanical. From your post, nothing points to mechanical as there should be nothing magical between 4400rpm and 5000 rpm.

Fuel? Could be a fuel starvation problem. But it doesn't sound like that to me. Is it sputtering or a real drop in power? Maybe you should put a pressure gauge on your fuel rail and bring her up to 5000rpm. If you see a significant pressure drop, you know where to look.

Anyway, assuming this is a stock setup with stock FI, it appears to be electrical. At the higher rpms, the dist is spinning pretty fast and a cracked dist cap or some such nonsene can cause significant power drop over 4000 rpm. In my case, even though there was no indication of a problem with the cap, a new dist cap completely resolved upper rpm power loss.

But first of all, isolate it to fuel, spark or mechanical. You;ll save your self some time. (IMG:style_emoticons/default/idea.gif)

... And let us know more about your setup.

it does have stock djet fi. ive tried different caps and such nothing changes so maybe something else ignition or like you said fuel. but i think its ignition because the tack will surge at times.

surge also?... what about a blocked fuel filter or even weak fuel pump, sounds fuel related over spark if both surge and high r.p.m. (flow) are the same issue

make sure of good flow/pressure

sorry but when i said surge i should have said the tach will jump around a it will jump to like 3500 when the engine is actually running at 3. and theres annoying pop in the exhaust when it cuts out. but i have been tinkering with it and ive gotten rid of the cutting out but it still has annoying little pop in the exhuast. i think that i have a small leak in the exhaust system and unburnt gases are lighting off.not sure tho.i post if anything new comes up.