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87 2.5 running rough

mattyg

NAXJA Forum User
Location
Victoria,BC
well i swapped in a 92 2.5 in place of my 87 motor with 200k less kms
i reused the renix tbi stuff aswell

i haven't run it on the street yet
when i start it up it idles a little rough but when i give it some gas it sputters and smokes out the pipe
i have searched lots but not that many 2.5s out there i am thinking either
O2 sensor, timing off by a tooth or so, or injector problem
funny thing is when i first did the swap it ran great, i left it for about a month and it started running rough, i am stumped and hate replacing parts to diagnose problem any help would be great
thx
matt
 
First, the free things. Reset the computer by taking off the battery terminals for about 5 minutes. Then check you fuel pressure and compression. After that, start with the coolant temp sensor, O2 sensor and then the fuel injector. You can get a rebuilt injector on-line for about $60. If you are running platinum plugs replace them with oem ones. Any other symptoms?
 
HossHoffer said:
First, the free things. Reset the computer by taking off the battery terminals for about 5 minutes. Then check you fuel pressure and compression. After that, start with the coolant temp sensor, O2 sensor and then the fuel injector. You can get a rebuilt injector on-line for about $60. If you are running platinum plugs replace them with oem ones. Any other symptoms?

i disconnect the battery after use, compression is good checked, motor has 80k miles on it
fuel pump was replaced due to noisy grinding original
not sure how to check fuel pressure doesn't have shrader valve like the 4L has
how do you check the injector (just look down TB to sight flow)
the whole ignition system was replaced cap, rotor, plugs, wires, coil and module

other symptoms
well i think the coolant sensor is not working right cause when i let it idle for awhile (20 or so min) i don't get a reading on the gauge, doesn't move but the coolant is hot, but this shouldn't matter should it because it sputters and stumbles right after flash up when it is cold already

a while back i was tracking down a turn signal problem and i had to turn the ignition on and off a bunch of times, in turn priming the fuel system, maybe i flooded it and when i flashed it up burned out the o2 sensor, i don't know

all i know is after the motor swap i ran it all day on the street and it ran like a champ other than the ps pump getting a little toasted (replaced)

is there a way to check the o2 or coolant temp sensor?
 
The coolant temp sensor can make it run very rich. From what you describe I would start there. The coolant temp gauge has a separate sensor. There is a way to check the sensor if you have a Haynes manual it gives the resistance. I don't have access to a manual right now so you might have to make another post to see if someone else has it. Keep me posted. I run a tbi system also and have had it run like crap too. Check your catalytic converter for blockage.
 
Double check the spark plug wiring order. The firing order is cast into the intake manifold.
 
HossHoffer said:
The coolant temp sensor can make it run very rich. From what you describe I would start there. The coolant temp gauge has a separate sensor. There is a way to check the sensor if you have a Haynes manual it gives the resistance. I don't have access to a manual right now so you might have to make another post to see if someone else has it. Keep me posted. I run a tbi system also and have had it run like crap too. Check your catalytic converter for blockage.

where is the sensor located for the gauge, the one for the ecu is on the driver side back end of cly head correct?

No cat i live in an area that doesn't require air care or smog check
i just run a loud cherry bomb glass pack for now, i'll have to change it out cause it annoys the hell out of me
 
old_man said:
Double check the spark plug wiring order. The firing order is cast into the intake manifold.

yah i triple checked that, when i did the motor swap i had the timing off a bit and backfired pretty bad out the exhaust, but after i adjusted it it ran great for one day of testing, this has been a year long project build due to a busy schedule
 
where is the sensor located for the gauge, the one for the ecu is on the driver side back end of cly head correct?

The temp sender for the gauge is the one on the rear drivers side of the block, the one for the ecu (on my 93) is right at the thermostat housing.
 
well i got myself a new 02 sensor 90 dollars canadian so like 35 cents US
any way plugged it in go to start jeep batt is dead, can't find the jumpers so i hook up the charger while waiting for it to charge i pull all the engine sensors out and clean the terminals with some emry cloth and some eletrical connector cleaner
after a while i go to start it well my starter is doing the clicky clicky it soon turns over and flashes up, at first it is running rough sputters and dies dam this sucks, crank it over again flashes up runs rough give it some gas backfires through the throttle body and dies great third time the charm
she runs rough give it some gas backfires doesn't die but starts to smooth out give it gas rev it up a bit idle smooths out 75 percent better still not thje greatest but it is not sputtering now when i rev it up ha to shut it down to sit the kids tomorrow i run it again stay tooned
matt
 
I have the FSM for a 1986 2.5 TBI. It may be able to help you.This could be a symptom of the TPS or throttle position sensor or the ISA motor Idle Speed Actuator. Rough idle would make me lean to these items. Backfiring through the TBI would lean to timing intake valve is open when exhaust should be hense a backfire through TBI. Keep us posted
 
tweakado said:
I have the FSM for a 1986 2.5 TBI. It may be able to help you.This could be a symptom of the TPS or throttle position sensor or the ISA motor Idle Speed Actuator. Rough idle would make me lean to these items. Backfiring through the TBI would lean to timing intake valve is open when exhaust should be hense a backfire through TBI. Keep us posted

when i say rough idle it is not revving up or down just not idling smoothly
i am almost sure the timing is set right i think all the backfiring was, was the intake manifold partially flooded and the excess fuel backfired off no other explanation
man i hope it is not he TPS or ISA i am sick of replacing parts 50 bucks here 90 there being in the navy i only get 4 or 5 months at home a year and i want to start driving my shit and not fixxing it
oh well just empty every pocket
 
Your in the Navy oh shit. I was to! where you stationed at.I was on the USS Vancover LPD 2 and The Uss Bagley FF1069 out of San Diego CA. Sorry to tell you this bro but thats what it sound like to me. Can you gas it and is it smooth or does i stumble. Because both of those control idle and revvving. A lot of times it is a ground on the unit itself you can check this with an multi meter. Good luck
 
The timing is not adjustable, it is read by the cps. Which is another one of those sensors that can affect idle. The cps should read no continuity across wires A and B. Usually if the cps goes bad the engine doesn't start.

The tps is easily checked by back probing. With the ignition on you should read 200 millivolts fully closed and around 4.8 volts full open.

The coolant temp sensor should read 7000 ohms or greater, engine cold, and 1000 ohms or less, engine hot. Unplug the sensor to check this.

The idle speed actuator only affects idle speed. It raises the idle speed until the engine reaches normal temp. Probably not a factor. They are loud.

Now that everything is changed, unplug the battery and reset the computer before firing it up again.

Other than the rough idle, how is the engine running?
 
HossHoffer said:
The timing is not adjustable, it is read by the cps. Which is another one of those sensors that can affect idle. The cps should read no continuity across wires A and B. Usually if the cps goes bad the engine doesn't start.

The tps is easily checked by back probing. With the ignition on you should read 200 millivolts fully closed and around 4.8 volts full open.

The coolant temp sensor should read 7000 ohms or greater, engine cold, and 1000 ohms or less, engine hot. Unplug the sensor to check this.

The idle speed actuator only affects idle speed. It raises the idle speed until the engine reaches normal temp. Probably not a factor. They are loud.

Now that everything is changed, unplug the battery and reset the computer before firing it up again.

Other than the rough idle, how is the engine running?

it is revving up better now put still sputters/stumbles a bit
idle is rough, not sure on rpm cause i have no tack, flucuates a bit
tomorrow i will double check my timing might be out a tooth, i did have it apart but i thought i had it dead on i'll check again
gonna check intake manifold bolts might have come loose causing a vacuum leak
i'll check the egr Vv
maybe if i hae time i'll pull off the TB and give it a good cleaning

and as for CTS i have one for the gauge right and one for the ecu
i can only find 1 on the head i can't find the other one this is an 87 2.5 so it might be different from the 4L, not sure though

i can't find hardly any info on the 2.5 renix motor i am just using 4L info as much as possible most stuff is the same but stuff like the CTS location is pissing me off
thx for the advice
 
tweakado said:
Your in the Navy oh shit. I was to! where you stationed at.I was on the USS Vancover LPD 2 and The Uss Bagley FF1069 out of San Diego CA. Sorry to tell you this bro but thats what it sound like to me. Can you gas it and is it smooth or does i stumble. Because both of those control idle and revvving. A lot of times it is a ground on the unit itself you can check this with an multi meter. Good luck

my location says victoria bc so that makes me a canadian sailor, the drunkest kind lol, we are so undermanned here we are never home the majority of canadian don't even know we have a navy
i serve on the hmcs protectuer we are a tanker supply ship and i am a marine engineer, we are a steam ship so the tech level is pretty low nun the least interesting, i got some good civilian tickets dealing with steam power that should hook me up civi side
i have been to Diego a handful of times, pearl hrbour, frisco, seattle
i always have a good time when i am down south, i love california my favorite place in the states for sure, i wanna make a wheelin' trip next year to the dunes in orgeon then the rubicon if it is still open
peace brother
matt
 
mattyg said:
well i swapped in a 92 2.5 in place of my 87 motor with 200k less kms
i reused the renix tbi stuff aswell

i haven't run it on the street yet
when i start it up it idles a little rough but when i give it some gas it sputters and smokes out the pipe
i have searched lots but not that many 2.5s out there i am thinking either
O2 sensor, timing off by a tooth or so, or injector problem
funny thing is when i first did the swap it ran great, i left it for about a month and it started running rough, i am stumped and hate replacing parts to diagnose problem any help would be great
thx
matt

First off the Renix manuals are online (including the 2.5, I think, as my hard copy FSM shows the 2.5 Renix ECU and Sensor details and the online copies are pdf scans of these) at http://autos.groups.yahoo.com/group/RENIXPower/files/

I would try adding some good quality fuel injector cleaner (get one that also claims to handle water in the gas, possible water condensation from setting up and not running for a while?) with the gas. Also check all the grounds and connectors starting with the battery for poor corroded contacts. May have corroded some setting up and not being run.

I have had older carburated cars even do that (start up rough, back fire, choke and puke a while after setting up a while with out being run. They just needed to be warmed up and run a while and then they were fine.

I doubt it is the O2 sensor. Try disconnecting it and see if it runs OK in the open loop mode! The O2 sensor seems to affect gas mileage a lot, but never caused backfiring or rough running when mine was disconnected for a while after an unfortunate encounter with the exhaust manifold.

Mike McGinness
South Houston, Tx
 
Ecomike said:
First off the Renix manuals are online (including the 2.5, I think, as my hard copy FSM shows the 2.5 Renix ECU and Sensor details and the online copies are pdf scans of these) at http://autos.groups.yahoo.com/group/RENIXPower/files/

I would try adding some good quality fuel injector cleaner (get one that also claims to handle water in the gas, possible water condensation from setting up and not running for a while?) with the gas. Also check all the grounds and connectors starting with the battery for poor corroded contacts. May have corroded some setting up and not being run.

I have had older carburated cars even do that (start up rough, back fire, choke and puke a while after setting up a while with out being run. They just needed to be warmed up and run a while and then they were fine.

I doubt it is the O2 sensor. Try disconnecting it and see if it runs OK in the open loop mode! The O2 sensor seems to affect gas mileage a lot, but never caused backfiring or rough running when mine was disconnected for a while after an unfortunate encounter with the exhaust manifold.

Mike McGinness
South Houston, Tx

thx for the advice folks
well today i screwed with the timing, retarded dist. 1 tooth, flashed up and it seem to run the best it has in a while, didn't stall out during warm up and doesn't sputter/stuble as bad while revving out, still not happy with the way it is runnig
so i desided to pull the Throttle body apart and clean it, the fuel that was in the pressure regulator diaphram spring assembly was brown and dirty as shyte nasty, the tank is almost empty
whats a good solution for cleaning out the fuel system, what is a good way to clean the injectors, i got a new filter, i haven't inspected the old filter yet i will tomorrow
matt
 
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