only sparks when testing cps?

[dcmarf]

95 GST -I have been having a spark issue and found that I have spark while testing the CPS by using a meter. I put the meter on the signal wire and ground on the engine and it will spark??? Any ideas why it wont spark when Im not testing it?

 

[sharky559]

I had the same problem for awhile bro. I had replaced the cps and no luck, about one month later i found out that i had blown a ground sensor on my ecu. i replaced the ecu and had no more problems. but if i was you i would get a new cps and go from there. maybe a bad wire some where. but good luck bro

 

[dcmarf]

That makes so much sense bc I have been thinking its a ground issue I just dont have a bad ground on the car but in the ecu I wouldnt know. Thanks for the info

Do you know what made you blow the sensor??? I just did a swap and probably did something wrong that may have blown it???

 

[sharky559]

well the last owener of my car kept messing with the harness. i think he was trying to install a safc. but when he took it off, the guy didnt do a good job on sodering the wires right. just check you wires and connections good. sometimes the harness plugs look the same.

 

[luv2rallye]

95 GST -I have been having a spark issue and found that I have spark while testing the CPS by using a meter. I put the meter on the signal wire and ground on the engine and it will spark??? Any ideas why it wont spark when Im not testing it?

Sounds like ground wire is open somewhere. CPS black wire is not making it to ground, and/or to ECU pin 13, and/or ECU pin 13 is not connected to ground inside ECU.

 

[dcmarf]

I chased the wires and dont see any cuts in the wire and its definitely hooked up to the ecu so thinking of trying a new ecu.

 

[sirmon]

Not sure but maybe it could be the cps plug. I hate to tell you to cut the plug off and wire it straight up but it might work? GL

 

[dcmarf]

Not sure if I wanna cut the plug off? If I did I quess I could run the ground wire to the intake manifold ground wire??

 

[luv2rallye]

Yes temporarily connect the CPS black wire to a ground (before cutting the plug off) to see effect. And before paying hundreds for a new ECU, open up your ECU and make sure pins 13 and 26 (ground connections) don't have melted foil paths on the circuit board (which you can fix). Sometimes a short in the right place can melt these due to excess current. Also check for leaking capacitors on the board while you're in there.

 

[dcmarf]

So you think I should cut the black cps wire and ground it or is there a way to connect it to a ground without cutting it? Maybe with a safetypin into it then a wire connected to the safetypin? I looked at the ecu and opend it up and it looks to be in great condition (nothing leaking for sure)

 

[luv2rallye]

Either use a safety pin or unplug the connector and if possible, connect the black (on CPS connector half) to ground and the other 2 to their correct pins on the other connector half.

Also make sure the ECU case has it's wire to ground in tact (outside of case).

 

[dcmarf]

Ecu case wire to ground????dont have a wire off ecu case going to a ground? Where is this wire supposed to be?

Is it off the case or in the wireharness bc my case has no ground wire coming off it. Just 3 bolts holding it on to the bracket in dash

 

[luv2rallye]

I'm sorry - never mind. I for some reason was remembering a bad ECU harness ground wire connection (discussed here: http://www.dsmtuners.com/forums/newbie-forum/267128-short-computer-problem.html#post151247670).

 

[dcmarf]

Well I tried running CPS black wire to ground on intake mani but no change still wont spark or start. Just turns over all day and never starts. I also see where the ECU is grounded (its in the harness to the frame in the dash). Still thinking I got a bad ECU?

ALL THIS WITH KEY IN ON POSITION NEVER TRIED CRANKING
When I tested the CPS and the CAS the Black ground wire shows like 42ohms on each and if you check it for volts it shows 7.8 Volts on each?????Why would it show volts and these ohms are way high right?
The Blue Signal wire showed .396volts way low on both cas and cps??
The red wire on each showed 12.7 volts so good there but the signal wire and ground wire are mixed up.Would this be the ECU orCPS/CAS????

 

[sirmon]

What is the signal wire doing while cranking?

 

[dcmarf]

The signal wires showed the same thing while cranking around.396 volts not sure what to do?? Any advise would be great. Im thinking its the computer or CAS/CPS?

 

[sharky559]

just take a quick look at your ecu bro. look for burnt track or leads what ever there called. I had a disscusson on a blown grown sensor in my ecu. go to that seach fourm menu and type this ( ecu ground sensor blown ) my name should be on there i think i also have a pick of what you should look for

 

[dcmarf]

ok ill check out your discussion. I pulled the ecu already and opened it up and it looks fine???But I really dont know what to look for except leakage.

Just looked at the inside of the ECU and mine is not messed up like the one in the pic you had sharky. You think its my CPS then?

This is mine

another pic of mine -think its good?

 

[luv2rallye]

95 GST -I have been having a spark issue and found that I have spark while testing the CPS by using a meter. I put the meter on the signal wire and ground on the engine and it will spark???

Ok a couple things I need to clear up before proceeding (because something just doesn't sound right or I'm not getting exactly what you're doing).

1) When you say "I put the meter on the signal wire" do you mean the meter's positive lead to the CPS blue-white signal wire?

2) And by "ground on the engine" do you mean the meter's negative lead or do you mean a grounding strap/wire?

3) And by spark do you mean at a spark plug or a spark on a meter lead?

4) What setting on the meter? Volts, amps, or resistance; and what scale?

5) Do you have the grounding strap from intake mani to firewall there?

ALL THIS WITH KEY IN ON POSITION NEVER TRIED CRANKING
When I tested the CPS and the CAS the Black ground wire shows like 42ohms on each and if you check it for volts it shows 7.8 Volts on each?????Why would it show volts and these ohms are way high right?

6) You cannot measure resistance with key on (voltage will affect reading and may damage the meter). 42 ohms is bogus. Also between what and what are your meter leads?

7) Again this voltage is near impossible since the highest it can be is 5.0v. Between what and what are your meter leads?

8) Are you measuring things properly? Voltage is ALWAYS measured with the meter's negative lead connected to chassis/body/engine ground or battery negative terminal. Resistance is ALWAYS measured across something (wire, component) with no voltage present.

9) CPS/CAS signal wire at 0.4v is low but possible at slow crank. Remember you are measuring a narrow pulse average. Spec is 0.4 - 4.0v.

 

[dcmarf]

Hey ralley thks for helping -
1-Yes -meters positive lead to blue/white signal wire
2-the ground strap going to the intake maifold
3-I had spark at a spark plug when I would ground it to the intake mani ground with the meter on volts. Meter pos lead on signal wire meter neg lead on intake manifold ground strap make a spark plug spark??
4-on volts
5-yes ground strap is good
6-I got 42 bogus ohms by putting meter pos lead on cps ground wire and meter neg lead on ground to intake mani with car in on position
7-Got that voltage off ground wire on cps with car in on position. Meter pos lead on black ground wire meter neg lead on intake manifold ground meter on volts??
8-yes believe I am measuring properly I just measured volts on black wire because it is in the position in the connector the manual says the signal wire should be?
9-Ya I see that the signal wire while cranking is low on both but like you said its pretty much in spec

I have a good ecu and CPS/CAS?????What the heck is my problem here??Also tried to make it spark again by putting meter on volts and pulling a spark plug and putting my meter on the signal wire and on the intake mani ground and it wont spark(trick not working anymore?).New coil, PT,battery,starter,sparkplugs gapped.028, and fuel pump all new???I just put the engine in and have been having this no spark issue for a month and a half? The engine worked fine in the car I got it out of??

 

[luv2rallye]

Your car is a 95 but what year engine and ECU are you using?

When you measure volts on CPS and CAS wires, they must be connected (did you have them unplugged perhaps?).

Can't explain why you got spark that time by just applying a voltmeter. This would make no difference at all unless by applying the probes you just happen to move a wire such that it then made a connection. First measure resistance from firewall to intake mani while moving that mani grounding strap all around. Perhaps it isn't always making a good connection. Then no matter the result remove strap, clean both ends of strap and bolts, replace & retighten.

Here's some individual component tests you can do: http://www.dsmtuners.com/forums/new...art-no-fuel-prime-no-spark.html#post151265626

 

[dcmarf]

95 engine 95 ecu.
Alright I checked and cleaned ground its good. I figured out it sparks on cylinders 1and4 and then after turning the crank by trying to start it for a while it will start to spark on cylinders 2and3 but never on all 4 at the same time???
Coil is good so is PT. Wires and plugs good. Im thinking cas/cps. Thinking about putting a black top cas on it and seeing what that will do???What do you think Rally?

 

[sirmon]

I think your right since a 1g cas will replace both the cas/cps.

 

[dcmarf]

Ya hopen that will fix this wierd spark issue. Just need to find a blacktop cas for a good deal.

 

[sirmon]

There is a 1g cas blacktop on the classifieds look for buddaboost