hitmanpty

I find out last week that number 1 and number 5 cylinder are not working.

I did a little test, I disconect the injectors plug one by one. every time I disconect one I can hear and feel the change on the engine . but when I do this to cylinder 1 and 5 nothing happend,. and as you know in diferent ocasiones I had say tha my car is not at 100% so all this time I been running my engine in 6 cylinders

1- At first my atention go to bad Injectors. so I remove the injectors and sent them to the shop.. they say there were a little dirty but after cleaning and testing, now they are working find.

So I install the injectors back. and the same problem. 1 and 5 not working. injectors are fine,

2- I check the injectors plugs for voltage. I find Out I have voltage in every plug. about 0.5 volts (dont know if this is a correct spec ) but if all the other injectros are working with that same voltage I guest it most be right. so I have voltage in every injectors

I also did a test light check and I get light on in number 1 and 5 cylinder ok

3- Spark. is ok. I remove the spark plug and I have good spark

what can be wrong here. i have spark i have fuel. but no responce from this cylinder.

what other test can be done. or what direction sure i go now

DanielRicany

No compression. Bent or burnt valve, piston ring blow by, or bad head gasket. Do a compression test on all cylinders, drain the oil, test compression on all cylinders, add oil, test again, if the pressures are significantly higher in 1 and 5, but lower significantly lower than the other cylinders, you have bad rings. If the pressures do not change, bent or burnt valve or broken head gasket, also could be a warped head.

If you've ever overheated, you can probably bet that it will be a warped head.

DanielRicany

Also I should mention that your test for the injector connectors was incorrect. Get yourself a noid light or LED bulb, plug it into the injector connector and start the car, if it flashes consistently then the ECU and wiring for the injectors is not the problem. Also, test the injectors yourself with an ohmmeter, they should all be around 16-17 ohms of resistance.

DanielRicany

And also, if you have been running on 6 cylinders for a while, and the problem is not lack of fuel, your catalytic converter could have been damaged.

Cliff Harris

Measure the voltage with one lead of the meter on the engine metal. Disconnect the connector and probe the connector. The pink/black wire should measure 12 volts with the ignition on.

The light blue and light green wires on one injector will show 12 volts if the other injectors are plugged in. If NONE of them are plugged in the light blue and light green wires will show NO voltage.

Put the test light into the injector connector. It should flash when the engine is running.

Just BOB

I did an advanced search and found the following post responding to an individual with two dead cylinders. It provides a logical troubleshooting approach that checks the simple things before going straight to heart surgery (like headgaskets, etc.)
Considering how many times you had the distributor out when you were chasing your harmonic balancer problem, I would verify that the plug wires are on the correct cylinders. I am probably telling you something you already know, but for completeness, first generation chevy engines number the cylinders as follows: Left side of the engine (viewed from the distributor) is numbered 1,3,5,7, from front to back. The opposite side is numbered 2,4,6,8, again, front to back. The firing order is 1,8,4,3,6,5,7,2. This is so easy to mess up, I'd recheck it a second time, especially if you think you found and fixed a pair of switched wires.

If the plug wires are correct, I don't think checking for valve movement has been suggested yet. Camshaft lobes can wear down to the point a cylinder contributes little or no power. Personally, this is not the first place I'd look, but considering the things you have checked so far, my next step would to investigate the valve train, especially if you have lifters ticking from excessive lash.

Engines with swapped plug wires or worn cam lobes can run deceptively smooth at idle and light loads.

One person suggested a "broken headgasket". If your problem were on adjacent cylinders, a FAILED headgasket would be a prime suspect which could quickly be verified by a compression test. Warped heads were also suggested. I believe you have cast iron heads. Warpage due to overheating is far more common in aluminum heads than cast iron. At any rate, a warped head would manifest itself with low or nonexistent compression.

Lastly, the "Advanced Search" feature of the website is very useful. Don't use the search box at the top of the page. Instead, click on "Search" on the red banner (The banner that has "User CP" on the left end) Then click on "Click for Advanced Search" in the drop down dialog box. Then, type your search words in the box labeled "Search by Tag". For your problem, my search tag was Injector Wiring". Lastly, in the box labeled "Search on Forum(s)", scroll down and select "C4 Corvettes 84 - 96" then hit "Enter". This kind of search returns much more useful results than the general search box at the top of the page.

Good luck!

BOOT77

How do the plugs look for those cylinders?

Simple test, take a pop bottle or water bottle and put some water in it. Drill a hole in the cap 1/8" or so, w/e makes it easy for you too squirt some water where you want it. Warm up the engine and squirt the individual header pipes. If that cylinder is burning good it should burn the water off fast. Good simple way to spot a dead cylinder.

bassackwards

You made sure that the plug wires aren't swapped didn't you?

hooked073

the old fashion way but still probley the most relable way to tell if you have a valve train problem it is hook a vacume gauge to the car fire it up if the guage flucates real fast then you have a valve train issue. With 2 cyl dead I find it hard this car would hardley move. I would think it would be back fireing missing ect. But do the vacume test it will tell you many a thing

hitmanpty

hello

I just preform a preasure test-

the way I did was.first i preform the dry test. and inmediately preform a wet test.
and them past to the next cylinder. one at the time

I think the way I did was not correct. because I get confussing reading. my preasrure gouch hose was full of oil for the 3 cylinder reading. I dont know if this afect the test. I realice I sure do is every cylinder first do the dry test an them go back and do the wet test.

I also did not measure cylinders number 6 & 8 . very hard place to reach.

Any way here are my readings. what can you all tell me about this.


cylinder 1
dry 130 psi
wet 160 psi

cylinder 2
dry 130 psi
wet 130 psi

cylinder 3
dry 140 psi
wet 150 psi

cylinder 4
dry 155 psi
wet 150 psi

cylinder 5
dry 150 psi
wet 155 psi

cylinder 6
not preform test

cylinder 7
dry 150 psi
wet 150 psi

cylinder 8
not preform test

notes cylinder number 1 it have a significate diferance. and cylinder number 5 almost no change on reading. this two cylinders are the one not working.

also I did preform a leak down test on cylinder numeber one only. at 25 psi.

I remove the pvc valve on the valve cover. I can hear just a little air but very soft.

no bubbles from on the radiator. no sound from the tail pipe., no sound from the intake

did not preform leak down test.in any other cylinder. because wife start calling. have to paint a wall on the house

hitmanpty

I will re check the spark plugs wires. I just read on this post that any compression higher than 90 psi. it sure do the trick. I have 130 on number one

hitmanpty

I remeber last year I had problems with death cylinders. but my memory fail me. so I try to find that old threed. I find it allright.

At that time the same cylinders were death. 1 & 5. my old injectos need it to be change. so A memeber here help me and sale me a good set. I install the new set and I feel the engine much better. but it was not 100%. I never get back and check the death cylinders again. into last week (year later) just to find out I have the same problem. that I never fix.

here is a link of the old post in case you want to read it

http://forums.corvetteforum.com/c4-t...ow-to-fix.html


so now Iam 150 % that the injectors are ok. since I change them Ia clean them and tested in the lab.

I have volts power to the injectors , also I have good spark

I been having this problem since I first buy this car almost 2 and half years ago.

hitmanpty

wires double check they are ok

I just got and idea that I will try tomorrow. because is late now

I will swich the injectors wire plug. from number one to number 3. and number 5 to number 7.

just to see what happend. dont think it will be any change but is an easy test. just to double check the inj. plugs

hitmanpty

??????? any body

Cliff Harris

That is a good way to test the connections. Here is another way:

hitmanpty

people has suggest me those noid light before

But the main reason I am not using them.

first they don't sale that nice tool down here in Panama. also I will have to wait about 2 weeks to get the tool. and them I only going to used once.

switching plugs will have the same effect I think

Kevova

Condition of distributor cap? it could be "crossfiring"

hitmanpty

distributor cap is basicaly new. I isntall about a year ago. and the car havent move much because run so poorly

hitmanpty

I did some more test this afternoon.

just to double check the injector wires, I did as follow
first start the car. disconect inj. wire number 1. and inj wire 3. them conect number 3 wire on number 1 and number 1 to number 3. .

(cylinder number 1 same condition. not working cylinder number 3 ok) this tell me the inj wires and volts are ok

after that I want to double check the spark plug wires.

did the same change 1 to 3 and 3 to 1. and did the same on dist cap. start the car

(no condition change cylinder number one not working cylinder number 3 ok) this tell me spark plug wires are ok

change spark plug from a good cylinder to the bad one. seme condition . this tell me spark are ok


after that. I read some where on the forum. that some times you can have a intake gasket vacuum leak. An you can check that by spraying brake cleanner or wd-40. on the suspected area. and you supost to feel the changes on the idle.


well I did just that. and nothing happed. one important thing. I did not have brake cleaner or wd-40 at the time so I use carburator cleanner.

tell me if carburator cleanner will work as well????


another idea that ocurred to me. since I messed so much with the dist. in the pass. can something be wrong. with the dist. maybe timming. or something.

dont know if timing can afect only 2 cylinders and the rest be ok

hitmanpty