Misfire at idle 1200 rpm and lower
 

Ok so i have done a sure fire replacment motor all new seals top to bottom i replaced dizzy wires plugs o2 ignition coil south bay injectors. New ac comp. Smog delete also pulled the egr stuff but left the solenoid plugged in. Intake is ported alil for gasket matching newish tps last year and a half


Ok so when i first start the car it runs fine but when the engine starts to bring the rpms down the miafire starts. Will make video
Drives fine above idle but sitting in park n r d it misfirs

Re: Misfire at idle 1200 rpm and lower
 

Do you have an adjustable fuel pressure regulator ?
If so increasing the fuel pressure might help a lean miss.

Re: Misfire at idle 1200 rpm and lower
 

No i dont but i just changed my fpr like 2 days ago still the samei juat posted a video of my car on youtube. Its title is 92 camaro 3.1 misfire

Re: Misfire at idle 1200 rpm and lower
 

Can't find the video. Can you post the link here?

Re: Misfire at idle 1200 rpm and lower
 

92 camaro misfire problem need help. Sorry thats the title

Re: Misfire at idle 1200 rpm and lower
 

https://cimg9.ibsrv.net/gimg/www.thi...2cd6c91cce.jpg
https://cimg3.ibsrv.net/gimg/www.thi...2be108adb7.jpg
https://cimg9.ibsrv.net/gimg/www.thi...10295cc71a.jpg
Just the engine bay and what it looks like

Re: Misfire at idle 1200 rpm and lower
 

Here's the video for those watching the thread:

Re: Misfire at idle 1200 rpm and lower
 

Does pinching the return fuel line off have any effect on running ?
I'm guessing you have checked fuel pressure.

Re: Misfire at idle 1200 rpm and lower
 

Thats that video
been kicking myself with this for some time now just want it to run right just put alot of money in it

Re: Misfire at idle 1200 rpm and lower
 

Checked for vacuum leaks? Make sure all the lines are hooked up, and get a spray bottle with water and spray around the intake gaskets, injector bases, etc. Vacuum leaks are made worse at idle. May not be the problem but would be good to verify. Verified the timing with a timing light? Are the injectors you put in the same flow rate as the stockers?

Re: Misfire at idle 1200 rpm and lower
 

If i ported the intake to match would that cause a problem

Also if i spray the plug wires coil or dizzy with a squirt bottle what should happen

Also is diy spark plug wire a bad idea

Re: Misfire at idle 1200 rpm and lower
 

Only if you significantly increased air flow. If you only mildly ported it I wouldn't expect this much misfiring. If you spray the gaskets etc with a squirt bottle you should hear a sort of slurping noise if it's got a leak, and the engine might even out. Getting it on the coil or distributor shouldn't cause any issues as long as the boots are in good shape. DIY spark plug wires are fine as long as you have good crimps on the boots and they aren't resting on headers. Could always double check the firing order is correct as well, I know that when I first put my engine together I swapped two and didn't even notice until I was out driving.

Re: Misfire at idle 1200 rpm and lower
 

Ok so if i spray the plug wires and it jumps bolt of lightning comes out thats bad . going out to the car soon to check for vac leaks and spray the plugs and wires. If the plug wires are good nothing will happen.

Re: Misfire at idle 1200 rpm and lower
 

Ok so i spayed the plugs ,wires coil and dizzy all vac lines nothin
but i think i have a short between map sensor and firewall.
Facing motor back right ...the wire harness behind the head
could hear a sizzle car started running bad and died

Actually got codes finally. 33 and 34. So ima chase wires in the a.m.

Re: Misfire at idle 1200 rpm and lower
 

Also had the car running unplugged the connector to the map nothing changed

Re: Misfire at idle 1200 rpm and lower
 

Bout to go check wires

Re: Misfire at idle 1200 rpm and lower
 

How to test map sensor wires what am i looking for

Re: Misfire at idle 1200 rpm and lower
 

http://www.chevythunder.com/map_code_33.htm
http://chevythunder.com/map_code_34.htm
This is for tuned port injection but still applies .

Re: Misfire at idle 1200 rpm and lower
 

Ok couple questions

Was removing my egr and smog pump a bad idea
And since i did what would i have to do


Sysmtoms are getting worse


Will that 50 chip fix the egr and smog pump delete



Ok so brand new motor from surefire. Called and asked if valves were set to spec before they send it they said yes
i have not adjusted valves 300 miles since start up


Ok so recap
Misfire no acceleration it also backfired in the intake today
codes 33 and 34
Sprayed motor with pump up coulndnt find any leaks soaked everything
or jumping of ignition system
tested map found grond and 5v ref but could find computer signal

is there a way to test injectors with the harness connector in front of motor and how

Really losing it with this goin crazy........ I can make videos if it will help any of u

Re: Misfire at idle 1200 rpm and lower
 

Injector pulse ? Can be checked with a noid light.
Output from the map to the ecm is that the wire you can't locate on the map ?
Or at the 1227730 ecm ? F15 light green
Not sure what chip your referring too but a memcal can be reprogrammed to disable the egr and air pump etc.

Re: Misfire at idle 1200 rpm and lower
 

How do i test the green wire
gray 5v ref was 5v
Ground was 12.3

Re: Misfire at idle 1200 rpm and lower
 

3 bar map
http://www.robietherobot.com/storm/mapsensor.htm

Re: Misfire at idle 1200 rpm and lower
 

I dont underatand

Re: Misfire at idle 1200 rpm and lower
 

For testing Leo on engine off Voltage will very based on altitude.

Re: Misfire at idle 1200 rpm and lower
 

Dont know what leo is


Juat cleared computer did a restart idles like crap but dosent die. Misfire no codes
remember brand new motor new sb injectors dizzy pluggs wires new fpr new coil new battery new alternator timing seems fine all new 300 miles ago also spayed the crap out

Re: Misfire at idle 1200 rpm and lower
 

Of the motor found no vac leaks or jumping vaultage or shorting wires

Re: Misfire at idle 1200 rpm and lower
 

Ok called surefire motors they preset the valves to spec. I never did an adjustment now at 3oo miles. Bad?

Re: Misfire at idle 1200 rpm and lower
 

The jumpy tach is an indication of a secondary ignition issue.

> timing seems fine

Has it been checked/set on a warm engine with the EST/BYPASS connector open? Set it to 10* BTDC.

What is the do-hickey mounted where the MAP is supposed to be mounted? It can't be good for the MAP to be lying on top of the coil. It may even be causing ignition issues by putting pressure on the coil to distributor connector.

Two other issues not related to the misfiring is: need to put the A/C compressor rear brace back on. Otherwise the aluminum accessory bracket will break next.

Should also run an idler set up where the smog pump was removed. Otherwise with the A/C compressor engaged the belt will be flapping about causing issues. Can get an idler off another 3rd gen that didn't have the smog pump.

RBob.

Re: Misfire at idle 1200 rpm and lower
 

The dohickey is a bracket i made to hold the egr and maphttps://cimg5.ibsrv.net/gimg/www.thi...19d873aa99.jpgand what all is secondary ignition
i still have the brackets ill get them on at my buddies house

Re: Misfire at idle 1200 rpm and lower
 

No need to keep the EGR solenoid, the ECM doesn't test for it via the electrical connections. Can get rid of it, wrap up the electrical connector pigtail, and remount the MAP as stock.

Unless the chip/tune has been changed the ECM can still throw an EGR malfunction code (with or w/out the solenoid connected).

Secondary ignition starts with the ignition coil. Then includes everything between it and the spark plugs. Cap, rotor, wires, and spark plugs.

Is the ignition coil secondary tower high enough to get the wire between it and the cap snapped into place? Can cut the boot shorter if required.

RBob.

Re: Misfire at idle 1200 rpm and lower
 

Yes i did trim it down the orignal wire broke so it was what i had left

I did make the plug wires my self. So ill try plugs and qires first dizzy and coil are lifetime replacement

Re: Misfire at idle 1200 rpm and lower
 

Ok so i replaced the plugs and wires no difference
so i looked at the dizzy cap and rotor looked bad posting pics to see if anyone can tell me why my cap and rotor looka like this i did clean them back up and tried agian no difference so i took the dizzy to autozone to get it replaced intire dizzyhttps://cimg0.ibsrv.net/gimg/www.thi...42a541838e.jpg
https://cimg2.ibsrv.net/gimg/www.thi...72781a557e.jpg
https://cimg5.ibsrv.net/gimg/www.thi...c3d98b0ada.jpg
https://cimg8.ibsrv.net/gimg/www.thi...b805b202fd.jpg
why does it look like that
Still has misfire

Oh car was running i uplugged the map sensor and no differencein running???

Re: Misfire at idle 1200 rpm and lower
 

If u notice in the center it looks wobblie and now that ive thought for a sec it had a crap ton of play
well i get a new dizzy in the am im going to open it up infront of the and inspect it first and if its wigglie they really just need to swap the cap and rotor really. See what happens

Re: Misfire at idle 1200 rpm and lower
 

The cap & rotor look normal after some use. Recall that there is 20-thousand volts jumping from the rotor to as cap terminal every time a spark plug fires.

RBob.

Re: Misfire at idle 1200 rpm and lower
 

Ok replaced dizzy runs better

But heres a couple things still going on

Iac is wide open upon start hissing away

And when i press the gas it boggs and dies